Why would one need to sell anything to anyone after one acquires the first machine that can automatically build the others? Capitalist economies kinda suffer fr

Why would one need to sell anything to anyone after one acquires the first machine that can automatically build the others? Capitalist economies kinda suffer from Goodhart's law: money is a better metric for success in a capitalist economy than most metrics are but it's important to remember that money is only a token to stand in for work and materials (I'd argue that the value of materials themselves are really just the work of retrieving them but that's a different argument). Having money in reality is just having work and materials in potentia. So what happens when the materials can do all the labor? Workers are cut out from the loop of owners gathering more things to own, and this does not hamper the owners at all. Adding AGI to capitalism isn't going to bring about capitalism with AGI in it like adding salt to water. Adding AGI to capitalism is going to act much more like adding sodium to water. I don't see it happening this generation, which is I guess nice, but I'm not looking forward to the transition between what we're doing now and Star Trek post-scarcity because I have the oddest feeling that if you look closely at any society that has done that transition there's likely to be an extreme genetic bottleneck, if I may be vague about it for pleasantries' sake.