I understand your line of reasoning but think about demand and supply. This is actually not very relevant in GNU/Linux land because we are a small percentage of gamers, but conceptually one can "vote with their wallet". Also, using libre drivers, donating to them and reporting bugs would help them become better and improve the situation for everyone.
Sadly, the most important choice has to be made before buying the hardware. Once you are stuck with hardware that doesn't work well on GNU/Linux, you can't do anything about it. A good way out in this case would be to sell the hardware and buy something (maybe less powerful, since you are not selling at full price) that works well on FLOSS drivers.