I believe the OP underestimates the "other thing" that actually holds everything in the Bitcoin Network together. The Game Theory.
Why would an entity act badly on the network if it can cooperate, and earn more by being honest?
Bitcoin is the dominant hash power chain using sha256 so it wont have this issue.
Its more aimed at minority PoW chains. For example, minority hash power chains using the same algo can be attacked by non-honest miners trying to reorg the blocks (51% attack) and double spends on exchanges.
All decentralised PoW are theoretically at risk of these types of attacks.
If the attack can pay for the cost, and earn more profit than if it mined honestly, then yes. It's still in the Game Theory, plus the attackers can go back to mining Bitcoin, BUT what if there wasn't any other SHA256 coin to go back to?