Bot operators can already pay human captcha solvers as the paper mentions. So all this does is potentially replace those humans with AI, driving down prices for

Bot operators can already pay human captcha solvers as the paper mentions. So all this does is potentially replace those humans with AI, driving down prices for bot operators. As prices for bot operators decrease, website operators will increase the challenge and drive up effort for the intended website audience (humans) who are solving captchas instead of paying bots. In the end, the website operators will have to stop using captchas as the intended website audience will no longer be willing to solve harder captchas. Website operators can use alternatives, like asking for micro-payments, high enough to discourage most bot operators.