I disagree with you completely.

iPhones, Tesla might be overpriced "products" which the middle class might buy just to feel that he will be "rich" but bitcoin isn't a product, it's a currency itself.

There might come a time when something unnatural might happen causing no phone, internet and electricity but I don't see that coming for the next couple of centuries!

When that time comes, all bitcoin will have been mined long before that. And probably, human species will also go extinct. So who cares when that happens, everything will be destroyed let alone fiat or Bitcoin!