Bitcoin is worth what people will give for it. So, if people believe it has value, like the US dollar, it has value. And the argument that the fact that another cryptocurrency can come along is a good, but probably not great point. The US could destroy the dollar and make another currency.
That being said, I'm still a believer, until proven wrong, that Bitcoin is a solution for a problem that doesn't exist. We have easy and stable ways of buying/selling/trading. I can easily send money around the world in a secure fashion. I can easily use that same money at Starbucks to buy a cup of coffee either through green sheets of paper or holding my watch close to the payment device on the counter.
I have employees in VZ. VZ is a PITA with restrictions, their currency being crap, etc. Do we pay them in Bitcoin as every Bitcoin zealot would believe? No, they love their USD.
Plus, it's not easy to use. It's nowhere near as easy as cash/credit cards/venmo/Google Pay/Apple Pay/Etc. Find me someone who isn't a complete dork who gets obsessed over this stuff who is into it.
The fact that it was worth little awhile ago, and now has skyrocketed makes it less than ideal because it's got high volatility. Sure it's great if you bought a bunch of coins at $2k and held them, but it's a digital currency, not a speculative stock. Well, I guess it is more the latter.
You're still talking about now. If I owned a dealer and made loads of money to take on this risk of accepting BTC for one car I absolutely would.
More because it is more accessible, more exchanges, more merchants, more software, more hardware and yea being first helped a lot.
"Old habits die hard"
That's because you can immediately convert it to cash. This came up when the first Tesla was bought with Bitcoin. They immediately just turned it around for cash. If you were selling gold bricks you would take a train load of egg laying chickens if you could easily then sell them to a farmer. But we already have fiat currency to skip that middle step.