Until there's a wealth floor -- until everyone is fed, sheltered and has access to education, there needs to be a wealth cap. We, as a collective humanity, should not allow anyone to have more than, say, $20 million, until the basic needs of others have been met.
We need to define "have." "Have" as in have X$ as personally owned liquid assets? Or "have" as in having X$ invested in economic development?
I'd agree with you in the former case, but not so much the latter.