That's your issue, You have regret.
Here is some sage advise from Sam Elliot in the movie Roadhouse. Cut it the fuck loose!
The world is full of whiners and loosers. Which are you?
look where nobody else is and go there. Then when the world wakes up you have already been there done that and have years of experience. What makes you tick? What interests you? You have stated you want to write parsers, compilers and other great software. Is that what's really bothering you? You haven't made a great piece of software and you feel that you are a failure? I think you need to write parsers, compilers and other great software.
See you are your own best psychiatrist.