It requires fiat banking less than you might think, depending on what you are doing and what jurisdiction you are in. I am in Argentina. I don't personally do it, but I know a lot of people that live on cryptocurrency salaries (not "crypto gains" but actual money paid to them periodically in a cryptocurrency).
I find your last statement extremely unlikely. I think Ethereum has a pretty solid utility story (and I'm definitely not putting Ethereum in the "bullshit utility" bucket). Making Ether a security would severely handicap the US as a jurisdiction for what could eventually be a huge new industry. If you look at the statements from the SEC and CFTC chairs in congress this is stated pretty openly.
I think a useful metaphor is to think of cryptocurrencies as the "Internet of money". Handicapping the Internet might have been possible before the Internet, but these days, people will find a way to operate businesses in new jurisdictions that are more friendly (because they will use the Internet to figure it out together). And crypto money might go to these jurisdictions just as fast, since it's not hampered by banking regulations.
With that being said, it's hard to figure out the outcomes of such a complex landscape with so many forces at play. But there's my alternate view for you to consider.