I'm a former professor. I could no longer stand the elitism, tiresome institutional structure, and narrow mindedness of working in a university. After quitting the ivory tower, I still desired to continue my research, and discovered the pros and cons of being an independent researcher.
The most obvious plus is that I can research whatever I want, whenever I want, and publish in whatever publications I want. No more colleagues frowning on my choices. No more administrators denying my funding requests based on personal bias. No more crappy vanity research in unethical publications to stroke the egos of a tenure and promotion committee. It feels a bit like being in grad school again, where my creativity and personal curiosity can shine - only with more maturity and structure as guidance.
The cons are painful, though. Gone are the days I can submit 30 interlibrary loan requests for materials in a day. My public library only allows three requests at a time, which is practically useless. I'm spending a lot of time and money buying materials and traveling to libraries to get at resources. But, the traveling is fun at least. Even though it's all on my dime (that travel budget as a professor was a privilege I took for granted!), true research freedom is priceless!
Besides a lack of access to materials, the major con is lack of access to respect. Filling out a form - be it for access to an archive or submission of a publication - I'm always asked for my "affiliated institution." Well, I don't have one anymore. They aren't interested in where I used to work, or my publication history, or even the quality of research I do now. It's a major hurdle. Academics are often fueled by their egos, and they often only have respect for others at their perceived level. Don't have the right letters after your name? Go away! Aren't on the payroll of a university? Get lost! Urgh. I saw serious independent researchers get turned away and mocked frequently by these elitist pigs.
It is possible to make progress in your research without the credentials of an academic, even while being under scrutiny of many academics you'll come into contact with. You'll have to be a more efficient researcher and do everything the hard way, but it will be rewarding!
In the hard sciences I imagine it would be costly, too, to gain access to equipment you might need. It all depends on what your goal is. But give it a try, and live your dream! You have nothing to lose.