I think the weird part about it is how final it is. Obviously, that depends on what you believe. I suppose if there is an afterlife, there would be the potential to regret. Especially if it's worse- punishment or something. But if there isn't, it it's nothing after this, it's like @Praestat_Mori said- everything for us dissolves in that instance. Even if we had an incredible life, one second we'll be here, the next we won't. We won't be able to regret or mourn our wasted potential. It's a peaceful but weird thought.
So- I agree. It's like- what would I be throwing away exactly? My timeline would end. My awareness of myself would end (hopefully.) If I made that decision to CTB, it would be because life truly wasn't worth it by that point. I wouldn't be able to regret my decision.