It’s a lot more than just “a few dev hours”. You need to invest in training your testers on Linux, potentially purchasing new hardware, invest in programmers that can deal with writing for Linux, etc… Just because something like BattlEye has a checkbox for Linux support doesn’t mean that all it takes is to click the button and rebuild your game.
I put the phone down as the light coming from it is part of the reason your brain is staying awake.