"Pay for itself" is probably a bit misleading. The development of transformative AGI, under the control of a single company, has the potential to render the concept of "getting your investment back" quaint and obsolete for that company. They'd never say it, and maybe some of them don't believe it, but they're effectively competing to be in control of the future of civilization. (Meanwhile, the amount of CO2 they're burning in their bid is actively reducing the chances of such a future existing...)

Well the total world economy is in the $100T region, so I'd expect the argument is that if you only need to replace a small fraction of that with AI to generate an ROI.