Snup
Maybe your concern is that with the drop in transactions, miners' revenue will reducedrastically. And nobody will want to continue or invest in a business where they struggle to profit. This might reduce the number of miners and might affect the decentralisation of Bitcoin. Transactions will continue, but it has reduced over the years as people focus more on using Bitcoin as an asset rather than a currency. Bitcoin is a neutral asset; hence, people are free to use it the way they want. We cannot stop institutions from investing, nor people from putting money in ETFs. As Bitcoin adoption is increasing and as it becomes less volatile, I guess the use for payments will also increase.
I think a time will come when people would get tired of wanting to hold bitcoin more than they are willing to spend it as a currency and that's when the adoption of bitcoin must have exploded beyond where we are now, making bitcoin transactions inevitable for every holder. This wouldn't exclude the bitcoin ETF holders because they can't be holding forever.
Mostly why people invest through bitcoin spot etf is that they find it a difficult issue managing their private keys which is actually the standard of bitcoin holding. So it's correct what others assert that if you are not in charge of your private keys then you're not a bitcoin holder but just an investor.