the fun part about the alts is ... they're all priced in btc ... so if btc ultimately fails / severely loses value , so does every single alt coin ...
If that logic is good, and BTC is priced in USD, then if the USD fails/severely loses value

SO WOULD BTC!
And here I was, cheering the doom of that fiat economy... and now I gotta prop up the USD just to keep my BTC alive?

no, because bitcoin isn't attached only to usd, but to fiat in general, and its value is indipendent anyway, we give value to btc basing on fiat, but if all fiat currencies crash, we can give btc a value based on goods, we don't need fiat actually