Can Blackrock (over time) turn Bitcoin into an inflated taxed asset by approving this ETF ?

I don't know exactly where to ask or discuss this so I'll just post it here and see if anyone is interested:

• If USA approves the Bitcoin ETF doesn't it mean people will be able to trade and influence the price of BTC without actually owning any BTC ?
• Can't this ETF easily depeg from real BTC and devalue crypto in general ?
• Do you guys think this move might be a threat to the DeFi ecosystem since it might influence a lot spineless investors to move their assets out of crypto and back into Taxland ?