Probably wasting so much time trying to make languages work that weren't really necessary. I spent so much time messing with C++ and performance and it was pointless because CPU's went from 4.77 Mhz to 3 Ghz. Also I probably would have just headed straight for a top CS school instead of wasting time teaching myself out in the sticks or learning 20-30 year old tech at whatever local university is nearby. Literally a lot of schools are still in the cold war era when it comes to teaching.