So I currently have a job in software that I really enjoy, however I've always wanted to do research, so I applied to a PhD program in CS to study formal methods and security. I've accepted an offer from the school I wanted to go to and met my adviser who seems amazing and I have full funding for 4 years. Its a great situation to be in. I had accepted the offer after weighing all my options, however now that I've actually accepted the offer, I've been having cold feet. I was given a generous raise & bonus at my current job (that I didn't quite expect) and I really feel like I'll be giving up (or at least delaying) so many things in my life (housing, hobbies, traveling, etc.). Also, I'll be giving up the security that having a good salary affords (for example, I've had to take care of my mom a few times when she needed emergency surgery and being able to just fly out on a moments notice is really comforting and something I'll lose).
I feel like I made a mistake by not just pursuing the PhD after undergrad, but at the time I didn't know what I wanted to research so I felt it would be inappropriate to go without a clear goal/specific research field in mind.
So I guess, my main question is how should I go about making a career decision when it comes to the PhD? I was so sure I wanted to do this, but its felt wrong ever since I hit the button to accept the offer. I'd love to do research in formal methods, but I feel like I've borderline been spoiled by having a well paying job after living extremely frugally as an undergrad (had like 0 money & support structure during that time) and I don't know if I have the mental stamina to go back to that life. If you guys have gone from industry to a PhD program, how did you make that decision?