Working hard won't be enough. Valve "worked hard" to get developers to support the OG Steam Machine, and the result was basically the same as MacOS; a bunch of lousy OpenGL ports that break on every system update. Even if you write a native Mac or iOS app, you're not guaranteed that the runtime will respect your work in the future. So most devs just don't bother. Windows wears the crown for not cutting off it's leg to spite it's face.
Valve is able to succeed where Apple doesn't because they aren't obsessed with being king-of-the-ring. They're a software retailer, Valve makes more money when more PC hardware proliferates to new audiences. Apple could do this too, but they would have to swallow their pride and work with Khronos again. Hence the reason why iOS games are often the most demanding native titles on Mac.