They could've choose to go proprietary with all their software, locked down proton, locked down their OS, locked down their hardware, locked down everything. B

They could've choose to go proprietary with all their software, locked down proton, locked down their OS, locked down their hardware, locked down everything. But instead, proton is open source, their OS is based on one of the most open distros out there and they published a tear down guide (not the best guide, mind you, but it's trillions of year ahead any competition on their space). So yeah, they are doing it for the money, but they are one of the very few companies that understands that money come from users, and they seem to be doing very good for users. So don't kid yourself, it's not only for the money.