You do come across guys who experience the feeling of regret after having sex with someone. The sex was not very good. The sex was meaningless. It was just another NSA hookup, etc.They were both drunk, etc...

You do not come across guys who experience regret because they jerked off too often. Most dudes understand that they have got to get their rocks off, and that masturbation, at times, may be the best, most efficient solution available.
I have been several times in Burgas, Bulgaria, where the OP comes from according to his profile. Now, I may be wrong, but I have never gained the impression that the place is really rocking with gay life, especially once the neighboring Black Sea resorts close at the end of September. I imagine that being gay in Burgas, Bulgaria is not the very best of all the available options. Meeting other dudes for some fun and possible friendship, etc., may be a tad more difficult than in many other places I have traveled to...
So, if you realize that you are kind of wasting your life, your sexual prowess; that you are missing on the fun that you should be having, the feeling of regret may set in.
My advice: if you are not happy with anything in your life - change it. It always looks much more difficult than it really is...
SC