Early Access is always a bit of a gamble for developers. They are putting forth a project in progress that they plan to continue working on but still want people to pay for it. It’s also a gamble for consumers as it’s not as simple as reading a review or watching a video about the current state of the game. You need to trust the developer enough to finish the project even after they get paid.
Whether it’s because of their previous releases or through proof of concept, Hopoo Games has seemingly done the difficult by crossing the million sales mark for Risk of Rain 2 while still in Early Access.
Source: Destructoid Risk of Rain 2 crosses the million sales mark