Sure in some cases that will apply, blockchain is final, but if the size of the loss is large enough, the social layer/legal layer will act, if someone gets rugged most likely its bye bye bitties, but if its a whole bunch of investors, there's enough of an incentive to try and find who took the money

Not saying its perfect, but you will always have heat on your ass, look at the Bitfinex hackers, they took a few slip-ups and they were captured. So there's still a chance an ETF can recoup some funds