The alternative is that the online games they're protecting become infested with cheaters, players depart, and the game closes down because it's no longer a viable business.
It's not nice, I don't like running a kernel mode anti-cheat any more than you do, but I can see why it's necessary for preserving the competitive integrity of free-to-play shooter games like Valorant.
The DMA card still needs to be installed, have drivers installed, firmware, etc. The anti cheat tests for that (the cheaters do mask the device spoofing the name/vendor/etc). Having to make new driver/firmware every time the anti cheat starts to detect it is way slower then just new software. Though at some point they will probably just automate it so that every customer gets their own driver and firmware matched with only their cheat software making this way harder but we are not there yet (and you would have to get all of these signed so following the cert chain should make it easier to find at least whos stolen cert they are using)
Also the amount of people willing to buy another pc and DMA cards is way smaller making the chance of running into cheater in your match smaller.
Elephant in the room is that any behavior based solution that can reliably detect computer vision based cheating obviates the need for kernel level anti-cheat because it more or less solved the detection problem.
It's not nice, I don't like running a kernel mode anti-cheat any more than you do, but I can see why it's necessary for preserving the competitive integrity of free-to-play shooter games like Valorant.