Too many players, too much ease of access, too much of the potential has been demonstrated at this point. Could it go down 50% or more still? Yeah possibly. I sat through 2013-2015 when Bitcoin had fallen from $1200 and got stuck in the $180-$300 range for two straight years.
I don't think that's going to happen again, not least of which because there will be people like me that would be happy to buy and hold until whenever it goes back up again at that price, but sure, it's possible.
But zero, or close to zero? No. Even this guy's example of his company was only one company, not the entire stock market.