Aside from decoration, memory, self-infatuation or other personal reason, is there any non-personal reason in keeping the paper versions of one's college diplomas? Or can one just throw them away and present the electronic versions at the rare occasions when they are required?
Assume the degrees are from universities based in the United States, if that matters.
Keep all paper certificates always.
Depending on what job(s) you apply for, and whether they require a certain degree, you may be asked to present the paper version. I have been asked in my last few jobs to present the paper version (an electronic copy was only accepted as a temporary measure while I tried to find the paper one), though this is in academia where it required that you have these degrees.
Industry jobs may or may not ask, so better safe than sorry and keep the paper ones.
An former instructor of mine once told a story about the school where he earned his undergraduate degree. A decade or so after he graduated, the school completely ceased operations after enrollment languished, the school went bankrupt, and a large portion of the campus was damaged beyond repair by a windstorm. He has protected his original diploma like gold since then, as it very well might be the only official record remaining of his degree. When a potential employer wanted to verify his degree, there was no records department they could contact. Someone at the state's education department had to look at the original diploma and certify that it was authentic based on the format, the seals, etc (akin to how someone would authenticate a historical document).
A friend of the family graduated from a smaller college that has since been absorbed into a larger nearby school. It changed its name to match the parent school, "something Women's University". Since this friend is male, and his graduation date was before the parent school started admitting men, he frequently fails background checks when applying for jobs. Employers request a certified transcript that will have the new name on it, which makes them think he's doing a poor job lying about his degree. He always has to show them his original diploma with the school's original name on it and explain the merger/rename, which resolves the dilemma fairly easily.
Never get rid of any official document (diploma or otherwise), even if it seems like you can easily replace it. You may not always be able to do so. Things like this seem less likely to happen in the digital age, but digital data can go *poof* much easier than physical documents. Between software bugs, cyberattacks, and human error, you shouldn't trust the preservation of vital records to anyone other than yourself. Not to mention, digital formats are notorious for becoming unreadable as new technologies develop. We have readable copies of paper documents written millennia ago; meanwhile, I have a research report written in 2001 that's in a format no modern computer can read.
Not to mention, it would be rather depressing to think that I worked my tail off for how many years and all I have to show for it is a measly PDF file.
In addition to possibly having to present the diplomas for verification upon hiring in certain jobs, you may also be asked to present them (or verified copies) when applying for visas for certain countries.
So yes, keep them!
As pointed out by other answers, in Europe it is common that one has to present relevant degrees either as an original, or a notarized copy (or a certified translation of one of the former). In fact, this can go significantly further than the last relevant degree - e.g. in Germany, it is not uncommon to ask for high-school diplomas even for postdoc jobs (in the public sector, that is).
As pointed out in other answers, you can usually get a replacement document issued by your university, high school, etc., but given the small numbers of certificates to keep, I cannot see why one would want to risk that.
Anyone requiring a paper copy of a college diploma is also going to accept a certified copy of your transcript (which will include any degrees earned). Alternatively, you can request a replacement copy of your diploma. The above suggestions will incur a fee (a quick search indicates in the range of $20).
So, if you do not anticipate any immediate need, want to rid yourself of clutter, and are ok with a nominal fee should your situation change, toss it.
I live in Texas and I used to escape the Summer heat by teaching a course at the University of Calgary every Summer. I had to present my diploma at the border to get my work visa each year. That's just Canada. How much more this would go for less neighborly countries.
In Europe they usually ask for the real diplomas signed by the universities. Sometimes they ask for a translation into the language that requires it
Think of keeping the paper diploma as a kind of insurance policy. You “pay” a small “premium” in the form of allocating some space in your house to hold a piece of paper (probably together with other important paper documents). In return, you have protection against the very low-probability event that you will someday need that piece of paper. This also buys you peace of mind.
The benefit of getting insurance to protect ourselves against unlikely but unpleasant occurrences is well-understood. This one has a zero monetary cost so it’s an even better deal than most types of insurance. If you find it reasonable to pay for car insurance, health insurance, dental insurance, or any other form of insurance, the decision to keep your paper diploma should be a no-brainer.
My diplomas and certificates are in a drawer. I moved them every time I moved. But I have never used them. Conceivably, if my career had taken a different path that it did, there might have come a time when it would have been appropriate to frame (some of) them and hang them in a grand ante-room to my palatial office.
Remember that paper documents are easily forged - all it takes is a printer and some fancy paper. Back in the day this was harder to do, but these days any kid can fake up a certificate in Word. No sensible employer will rely on paper documents these days. That's not too say that there aren't employers around with obsolete ideas about this, but they're dying out. I've worked in industry for 25 years and I've never been asked.
If you attended a reputable university in a G20 country, the master record for your degree is not your paper copy, it's the university records. If someone wants to know if you got a degree from the university, they call the university. Even if the university shuts down, the state will normally preserve records for exactly this reason. But most universities in G20 countries don't shut down, because the trend is for increased higher education. At most they might merge with another university, but the historical records will still be preserved.
All this assumes anyone cares about your degree, of course. Remember that a degree is only a beginner's qualification in that field. Within the first few years of uni, your degree is going to be a major part of your "show reel" for getting a job, sure. After a few years of real work though, employers are far more concerned with the work you've done. A degree only proves that you've had some teaching - your experience at work proves whether you can apply what you were taught.
And even when you've only got your degree, as an interviewer I don't care about the piece of paper. I want you to talk me through the major projects you did, what the challenges were, and how you solved them. I want you to be able to geek out on the details - and after 25 years you'd better believe I can keep up with you on that! I want someone who's as excited to be working in the field as I am. If all you can tell me about is passing exams, you aren't the person I want working for me.
All this does assume that your degree was in any way relevant to the job you're applying for. If you're going for a completely different job, and the company is using "do they have a degree?" as a placeholder for "do they have a functioning brain?", then maybe they're more likely to want proof of a degree even after some time.
But I take exception to that attitude, because it implies people who've chosen to do some other line of work instead of getting a degree are somehow "lesser". The best engineer I've ever worked with, who mentored me for a number of years, started as a technician and got a degree in his free time a number of years later. I'd strongly disagree with any suggestion that he was ever "lesser" before he got his degree. So if this is the mindset you're faced with, you should think carefully about whether this is actually a good place to be.
