You sound... Really obnoxious. And a little high on yourself. You do realize MOST people grow and change immensely between the ages of 17-25. So he changed. Like normal people. Experiencing the world, seeing things differently, becoming more outgoing. Yes sometimes we are introduced to things by others, that's cool. But clearly he taught you things too. Honey this probably wasnt JUST because you so called made him a better person. Geez that's a bit self absorbed. Maybe you don't realize it sounds like that. But honestly you have a little growing and maturity to do also.

Let him live his best life, and your live yours. And try not to take responsibility for the natural growth others go through. In glad you were part of it, and maybe you did introduce him to things, but you didn't make him who he is.