Life is something everyone should have. But life is not something youi can count on. It is easy to end, but not as easy to begin. I am not talking about death, or birth. I am talking about living. Every one dies, but not everyone lives. Many do not know how to just "throw caution to the wind". That doesn't mean being stupid and drinking or drugs, it means take a chance, do something with your life. Don's land a job, get a career.
Regret. We all regret something. Like not asking some one out, and then you lose them. But the regret I talk about is the one that could end a life. You hear someone talk about suicde, yet you don't stop them. Yes it is your fault. Regret never goes away, it stays with you till you die.
But the question asks, "Why does not living cause regret?". Answer is simple. If you do not live, you will regret it. Give up being so serious all the time. Have fun. Life is to short to be mean, or quiet all the time. Live your life how you want to. be who you want to be. No one can stop you as long as you don't let them. Just breathe. The trophy is waiting for you, now go get it.