Couldn't Windows users boot into Linux then to get games for free? Like, it would probably increase the share of Linux users but Windows users would decrease. And when you start charging for the Linux port, a large amount of those users would flock back to Windows.
dual booting is a kinda a lot of work just for some free games.
You also could charge a dollar since you are often offering a strictly worse product for Linux users. That's what happens in many other markets when you are trying to expand a userbase.
There is clearly a dollar value to providing support. Why shouldn't the price reflect that?
