The ones that decides this are the people that has invested heavily in mining hardware. Why would they move to PoS and make their whole investment worthless??
I always thought about this too, but the ETH miners also resisted ETH 2.0 (which essentially was moving from PoW to PoS) and in the end they also started getting behind it.
I think ETH miners would love it. Stake the ETH they were mining during the grace period, then move their hardware to other PoW alts. Bitcoin people would probably never consider it though, or would they?