[seabee]

Even if you ignore the problem of getting a critical mass, this is an issue!

Imagine operating the network as a public good and agreeing to minimise the resources spent on it. That still doesn't prevent one of the players from secretly increasing their computing power then suddenly taking full control of the network and disrupting other countries' economies.

The incentives means you don't have to trust anyone else - you'll keep improving your CPU power because it makes economic sense to do so.