so there's always going to be other vehicles they can rotate their money into

That doesn't actually stop every asset from going to zero against BTC over time.
The only way an asset doesn't go to zero against BTC is outperforming BTC over multiple cycles...
Which very well may never happen although it certainly could happen and I expect it will eventually.

Very few traders have outperformed simply hodling Bitcoin.
Including myself, by a wide margin.