The problem with such ETP products is that they are certificates. The underlying value (i.e. Bitcoin) is not deposited as collateral. If the issuer goes bankrupt, the certificates become worthless. Just as with many previous exchange-traded products such as ETNs (exchange-traded notes).
The situation is different with ETFs, where the underlying value is deposited physically or it is replicated synthetically with other products (e.g. shares).
Unfortuantely, many do not know the difference and often equate ETPs and ETNs with ETFs.
The first time I read that they offer zero management fees, it provoked suspicion how an investment company dared to claim such a thing. It's clear in prospectus that it's not really zero even after counting higher than Greyscale as @exstasie said.
But to be honest, I support various derivatives of Bitcoin because whatever product is produced has its own market, we might not be interested because basically we already understand and know what BTC is like and how, but for those who don't want to be complicated with asset security because buying BTC in large quantities or set when to sell or buy then the best choice is a product like this.
It's true, sometimes people can't tell the difference between ETP, ETN, and ETF and even I myself still often confuse the terms. But again, whatever it is after the momentum of the approval of the Bitcoin ETF, although it is still futures and not yet in the spot, there have been many adoptions of BTC products that should be able to reach a wider community.