1. Do you want large institutional financial organisations buying large amounts of bitcoins and then locking it up in centralized trading platform
No body would want that but still we can't tell anybody what to do with their Bitcoin. For there to be a good side there has to be a bad side, and for the good to be appreciated the bad has to be present so by the time they lose their assets due to hack for storing their Bitcoin on centralized platforms, they'll learn of self/Non custodial ways of storing Bitcoin and that'll make them to pick interest in owing Bitcoin and not buying Spot EFT that they don't have control over.
2. Do you want Bitcoin to be a commodity or a currency? ETFs will destroy the goal of Bitcoin becoming a currency.
Bitcoin can be both, Bitcoin being a currency isn't happening anytime so if we're been honest with ourselves but that doesn't mean it won't happen in the future. To keep the spirit of adoption going, Bitcoin been accepted as a commodity is a welcome development because that'll help us reach to other audiences that'll all add to the popularity of Bitcoin and from there we can move forward.
4. Fiat whales get control over bitcoins and can be used to manipulate the Bitcoin price. (They control the traditional Fiat investment options, so they will gradually increase their ownership of bitcoins to control that too)
The whales can only manipulate the market for a short period, and by the way if the whales want to manipulate the market they can do that without the Spot ETF, controlling the media is enough power to manipulate the market as the market is being influenced by the media with the spread to fud but all this have temporary effect on the market.