Some devs. To think most or even half of all devs do this is a bit overly optomistic.

I meant in the sense of “if a dev doesn’t perceive it as slow, they won’t optimise it”, not that they’d necessarily optimise something that is slow.

However a dev on fast hardware can still run profiles, and the fast hardware decreases the change/build/test cycle by more than enough to make it worthwhile.

The only use of a slow machine is it gives a point where you can say more optimization isn't worth it. Everything else I can do better on a fast machine than a slow machine.

The fast machine lacks the most important element: the incentive to do optimizations in the first place.

It lacks one inventive. There are many incentives. Many developers love making things faster. Many developers get feedback from users which is itself incentive. Many projects track performance and that provides incentive. Many developers have a boss who cares about such things (this is the least likely of the above).