When it comes to people there's no answer for hard solipsism or idea like how do we know we're not in a simulation or a brain in a vat. All I can say to that is, there had to be a first civilization to make the simulation or put the jar in the vat, we could easily be that, there's more assumptions you have to take into account with more variables. For solipsism, I've always said hey if I'm the only one that exists and you're all in my imagination or I'm just in your imagination, you or I wouldn't make a world this shitty in my head, so, that argument is defeated.
If the hypothetical idea of an afterlife means more to you than the objectively true reality we all share, then you deserve no respect.
