If there was enough money on the table waiting to be picked up, Valve would know that. They have incredibly fine-grained detail of their user base on Steam, and they have multiple economists on staff to guide their decisions. It isn't worth it to them, and it isn't on them to bust out of that chicken and egg problem. They fixed the problem they already had (fear of Microsoft screwing them) by putting their eggs into the Linux basket.

https://www.valvesoftware.com/en/jobs?job_id=4