People see cryptocurrency as this idealistic alternative to fiat, but in all honesty, it's not. What people seem to forget is that the only way to obtain cryptocurrency is using fiat currency. I cannot honestly tell you one way you can obtain Bitcoin without needing to buy it via a service like Coinbase or some form of exchange. What everyone needs to realise is, if fiat fails, so does cryptocurrency.
And then you have the horrible anti-consumer process of going through KYC/AML requirements like; passport scans, drivers licence scans, utility bill scans, taking a photo holding up a sign and other stupid requirements to be approved to buy/sell and trade cryptocurrencies on exchanges.
Until my employer pays me in cryptocurrency, my phone company accepts crypto and I can pay my mortgage and life expenses using crypto (like fuel), fiat is the only option.
The only true alternative to fiat is precious metals like gold and silver, not volatile and easily manipulated cryptocurrencies. That's not to say Bitcoin and other cryptocurrencies in the future won't be stable or good alternatives, but right now they're a mess (look at the price of Ethereum for reference).
I am especially sceptical of these high-profile figures telling people to invest into Bitcoin given they probably have large sums of it and it's in their best interests to see the price go back up so they can sell some of it. Kim Dotcom has a well-documented history of fraudulent and illegal activity, I wouldn't trust him as far as I could throw him.
RE: USD is a Scam, Invest in Bitcoin/Crypto Before U.S. Debt Spirals Out of Control