Of course, big personal statements like Arthur Hayes, former CEO of Bitmex, must be taken into consideration, because the man has great experience in the market and knows what he is saying.
The point made by Arthur Hayes is that the liquidity in the market will decrease a lot when the instant Bitcoin ETF starts, because everyone will not buy real bitcoin, but will buy bonds or stocks, and this will reduce the liquidity in the market significantly while the amounts of bitcoin remain the same.
In any case, even if these predictions are correct, I think it will be a very good opportunity for those who missed it to buy Bitcoin at cheap prices before the expected explosion.