People spend whole lives in prison and they still don't want to die. Very small number of people with healthy brains (undamaged by depression for example) kill themselves intentionally even though it's not that hard. Life is very fragile. Somehow even in this world filled with suffering practical calculation lands for almost all people on the side of "let's not end this just yet".

You can ponder eternal torture and not existing but I'm talking about more down to earth thing. Your single life. You will never have anything besides it. It's not eternal torture, it's not even all torture. It is everything you own and the only thing you own. How could you give up any future piece of it that you didn't have to?