Why can't I collect on it?

Betting on systemic collapse of society has a challenge at the winnings collection point.

"Here's your trillion dollars. Go buy a slice of bread. Ooops… half slice. Well, quarter."

huh? he can just short the companies he's so concerned about

What good is that if the entire socioeconomic system collapses?

by shorting he can make money and give it back?