Simple reason that I can think of is that this is the only thing that's coming out of the mouth of many fund managers that want to sell something to their clients, bitcoin ETFs are a new thing and they can easily spin the narrative that this is a new thing and that if you invest now, you're one of the early adopters of the ETF which in the ears and the mind of that investors, it would sound really good that they can't pass up on the opportunity albeit the risk is tied with the volatility of bitcoin. It's actually pretty impressive that we're not even half a year to the approval of ETFs, they're able to get this much money already, goes to show that investors have a confidence that bitcoin's going to be a really big deal in the near future and missing out means that you'll regret things later when it inevitably goes up.