Not sure if crypto trading is actually a threat to stock traders since both are different asset classes.
Its like a Venn diagram, you got group A, group B and group A+B

Moreover, I believe stock trading cannot be as good as crypto trading, at least any time soon.
Have been doing it longer than crypto.

It can be profitable but if you want it to be steadily profitable you have to go long term similar to bitcoin.
The reason being that crypto trading happens 24x7 and has immediate settlement whereas stock trading runs only 5 days a week.
So crypto trading is better than stock trading but that doesn't mean it is threat to traders since the asset classes are very different.
The timing only makes crypto more risky, you cannot monitor crypto all through the night, but stocks you only see for half the day. It just the intrinsic properties of each market or asset type. It does not make one good or the other bad.