This seems like a peculiar realization to come to this late in your training. What is it that is not fulfilling to you?
I think most MDs/DOs have these thoughts during training. Especially those in surgical subspecialties or acute care settings (ED, ICU) due to the nature of the work. It's hard work, you see a lot of really advanced pathology -- and operate on it, you work twice as much as your friends outside of medicine and make less than if you would have taken a job straight out of college.
Peroxidase I would say that if it's a surgical issue - give it another year and see if you feel more confident in the OR. You will.
And consider that it may not be practice itself that makes you feel this way but may be in large part your current setting. If it's tiring clinical volume - consider finding a low volume job, maybe even part time, with some other people who seem happy. It would let you to see what the lightest of all options would be like.
Also keep in mind that the stuff we're seeing in residency is not the same as typical private practice patient population. At a referral center you see a lot of trauma, advanced pathology, difficult cases, etc - because all the hard stuff comes to you. It's great for training, but it slowly drains you over the years. Getting out into a different patient population may surprise you when it comes to your level of happiness. Some people call the first job out of training "IGB job #1." (It Gets Better). Don't forget that.
And for non-clinical jobs, there is an organization called
DropOutClub that links MDs to non-clinical jobs in industry.
I doubt you're going to find an investment banking position on there, but I also doubt that if you go down the investment banking / finance road that you'll be able to make $250-300,000 /yr with a reasonable workload. Maybe it's lucrative but it's risky, and Ophthalmology is far more likely to produce that end result. Plenty of unhappy people in finance working longer hours than we do.