Do you try to help them, knowing you're not the first and you won't succeed and you won't be the last, investing dozens of hours that you could be spending making cool things for your other members?
Do you ban them? There's a small but non-zero risk that they might literally kill themselves if you do that.
Taking no action is tempting, and would be the worst decision you could make.
I've been in this position more than once.
THAT'S a hard decision. It's NOT a hard decision to ban a nazi.
Aurin (ki, ki, kis)