I'd rather stick to the subjective theory of value which basically says things got their value out of people's need or desire for it. Man, Bitcoin may be a worthless piece of shit to you. But tell that to the millions of unbanked people, to millionaires and billionaires around the world trying to keep their wealth's worth, and to the richest man on this planet who finds Bitcoin a sort of a refuge in the face of a fiat currency which offers nothing but negative real interest.[1] If you say Bitcoin is worthless without fiat, then perhaps you need to go back to the start and try to get the tiniest of inkling about it.
Isn't that how fiat got its value too? If there were ever a collapse, billionaires and the people that are controlling the market will try to curtail the total collapse and I don't think that they will consider bitcoin because they know that ordinary people will have power if they were to consider bitcoin as a store of value in the event of collapse. I mean OP is somewhat right, bitcoin is basing its value on USD or other fiat currencies but if a collapse were to happen, I don't think bitcoin will be the first thing that will come to the minds of the people who needs to survive everyday.
Somehow, yeah, but fiat has a different case as it is a legal tender. You cannot not accept fiat, even if you find its concept a total garbage. That's what a legal tender means. Therefore, it is always understandable that Bitcoin is also priced according to fiat. But it doesn't mean its value is solely derived from fiat. In the first place, Bitcoin got value in terms of fiat because it has qualities worth giving value to.
You are probably correct that billionaires whose wealth are partially stored in fiat will try to save fiat from total collapse. However, they also understand things and probably have a very good sense of foresight. They diversify. In the words of Elon Musk, they're no fools and that they look elsewhere to store their value in the face of a fiat giving off
negative real interest.
[1] It so happened that Bitcoin is one of those alternatives which caught their radar. So you are wrong when you said that the billionaires won't consider Bitcoin.
And you are probably also wrong with your reasoning that billionaires won't consider Bitcoin because ordinary people will have power... They don't care because they can have as much Bitcoin, and therefore power, as they want. Whatever ordinary mortals consider valuable they can own and hoard a lot.
Finally, as to this "I don't think bitcoin will be the first thing that will come to the minds of the people who needs to survive everyday," we can only look for a case in real life, somewhere where fiat has already started to collapse, and it seems Bitcoin has indeed gained value there.
[2][3][1]
https://twitter.com/elonmusk/status/1362600676174557186[2]
https://www.nytimes.com/2019/02/23/opinion/sunday/venezuela-bitcoin-inflation-cryptocurrencies.html[3]
https://www.bbc.com/news/business-47553048
