I don't regret anything, as that would be a waste of time. However, I am well aware that I certainly did miss things. Every damn thing is a trade off. I partied extremely hard in my teens and very early 20s. Due to this, and the SES/culture I was born into, I missed ever being a big timer by getting into a top flight law, B, or med school. So I got to "exprience" many things dedicated students did not. Those students though, by being big timers, are going to experience things I never will, like leading wealthy lives in NYC, London, or Hong Kong.
That's just an example. Everything is a trade off. Regret nothing but try to make good cost/benefit style decisions.