I'd assume if someone knows how to flash (or in some cases optin) a beta, they know what they are getting themselves if not. If not, it's no different than a person opting into being part of a pharmaceutical trial without reading up what that is or entails.
That said, if a beta is in such a poor state that it's borderline unusable, it's IMO not a beta, it's an alpha. Betas should be nearly complete build with known and unknown issues but nothing system breaking. Not all betas come out that way but that's the proper order of things.