Google has chosen to invest all across the stack in numerous ways. Why do they have 180k people working for them? Because they design their own racks, build their own machines, built their own network, designed their own databases, built their own scheduler, created their own build system, and yes invested in developer tools. I don't know what the coefficients are for each one, but you can go find plenty of older software companies that only try a handful of these and skimp on the rest.

I don't believe any of those companies have as many billion dollar successes as Google. They aren't the only company to do this, but they certainly do it at an unprecedented scale.