The value is purely a function of speculative demand. And while previously people anticipated the demand would go up "organically" because of actual real-world usage, you know to pay for stuff and such, that hasn't really materialized in the way we hoped. How many actually use BTC for things like that? At its BEST it has usage to purchase other coins - but that's about it.
It is digital gold, but with seemingly less IRL usage. When I started with BTC 12 years ago, the community was really optimistic on the potential use cases - but mostly the aspect of it replacing expensive wire transfers, potential for being a digital currency you could use in your daily life.
After each hype cycle that belief diminished, and it became more apparent that people only buy it to get richer by the means of speculation.
The days of BTC 1000x'ing are long gone. Even if 1 BTC is to go for $1MM, that's "only" a 21.5x increase, and it would mean that BTC alone has a 21 trillion cap. That's half of the entire S&P500 market cap. And you'd still have a slew of other safe coins that competes against BTC for the same money.
So, my point is: While BTC is still the king of crypto, it lives in a financial market that is mostly driven by speculation and expectations of huge returns. The very same investors can earn a lot more by gambling on "lesser" coins.
There's still money to be made, but that boils down to people buying and selling between the various boom and bust cycles. We're 15 years into this now.