Lets not take is as a certainty. This problem might be beyond our capabilities. Its kinda like stating: When we invent warp-drive. We don't have a proof for warp-drives same as we don't have a proof for building AGI.
... except there is no proof. We have no proof but we talk about it like its a given. We talk about "intelligence" as if its an integer value that scales from 0 to infinity. These are ideas that we do not question enough.
I assert that its a possibility that we are incapable of building ourselves beyond reproduction.
Possibility means probability. So there is also the probability that we can build ASI, in which we should be very careful in our wanton abandon in attempting to create it.
Lets not take is as a certainty. This problem might be beyond our capabilities. Its kinda like stating: When we invent warp-drive. We don't have a proof for warp-drives same as we don't have a proof for building AGI.