Nobody is doing well enough with AI revenue ATM (https://isaiprofitable.com/). At the moment it is probably more about market share of users, that is where the investment capital will need to be clawed back from when it starts to be called back (or replacement money will need to come from if the investment cycle simply stops giving generously).
Online advertising has completely broken from anything resembling the traditional social-contract of magazine ads, billboard, signs, etc. They're preying on your safety and privacy, not just your attention.