Here i go again....
[disclaimer - what follows is not an argument that hell does in fact exist, just n answer to the question]
those who believe hell exists do so because their "holy" scriptures tell them that it does.
In the case of Christianity, the most vocal figure about hell in the entire Bible is Jesus himself.
also, it's worth noting that there is a potential distinction between the figurative descriptions of Hell (and Satan, btw), many of which come from works of fiction (Dante for instance) rather than from Scripture, and the existence of SOME place which Christ referred to as hell.
Now, there are - of course - many arguments, usually highly misinformed, that what you have in the modern bible doesn't at all reflect what the first century church or its founder actually said and did....but obviously the one who believes in hell doesn't believe them.
So, the "evidence" for hell is only and entirely what is found in the given religion's holy books.
By the way, and again, I'm NOT arguing FOR the "eternal damnation" version of hell BUT
the tired canard "I'd rather go to hell because that's where all the cool people will be partying" is nonsensical.
If it is not, in fact, a place of suffering, then it's not "hell" - if it is hell, it is by definition a place where no one wants to be and no one is having a good time.
Even if it's not fire and brimstone, it can't be hell if you can enjoy being there.