That's a big "if".
Most people have no reason to self custody because they have no need to spend coins.
Everything they want to spend money on is produced by the Fiat Dominion. There's nothing they want to buy that requires payment in Bitcoin. And so they only care about number go up, and the ability to off-ramp into fiat.
Thus, they are better off with a financial instrument that is linked to the price of Bitcoin because they are guaranteed to have an off ramp into the real Fiat economy that produces all the stuff.
And so we're on a direct track to a paper bitcoin market just like we ended up with a paper gold market.
Unless Bitcoiners actually start producing goods and services more efficiently than Fiat companies, we have no need for Bitcoin to scale.
This is also why governments and bankers aren't terribly concerned yet, they don't just print money for free, they also gate keep the global economy.