Gaming

Getting direct3d and vulkan working with actually useful performance

They definitely spent an ass-load of money on that

[citation needed]

I'm not aware of Valve or Doitsujin ever revealing how much they paid him to make DXVK. I assume they paid him reasonably well, but I doubt it was an ass-load.

the fact that Wine was around for 25 years before that just goes to show that no one else was willing to do that.

Or maybe that Wine was a lot more work than the direct3d-to-vulkan shim that was done mainly by one person (now two people).

Valve definitely helped by funding a few key projects, and packaging them in Steam made them convenient to use, but I think exaggerating their role unfairly diminishes the much larger body of work (done by other people) that makes it possible at all.

Proton stands on the shoulders of giants.