I don't understand how people are upvoting you for being rude.

Because you're a troll.

I would like to see Valve start a campaign to move people to Linux and to combat Microsoft.

Why would that be a stupid business decision?

Why wouldn't Valve support people moving away from a prioprietary, closed system?

Because Valve is a business. They don't exist to be a proponent of open source, they exist to make money. As a game publisher, you do that by offering your products for the most predominant home computing platform - Windows. You don't burn research and development money on a niche platform that 5% of people use because there's no return on that investment.

I think it's you who didn't think it through.

No, it's you. You don't think at all.