The AGI would have to acquire new resources slowly, as it couldn’t just self-improve to come up with faster and more efficient solutions. In other words, self-improvement would demand resources. The AGI could not profit from its ability to self-improve regarding the necessary acquisition of resources to be able to self-improve in the first place.

If the AGI creates a sufficiently convincing business plan / fake company front, it might well be able to command a significant share of the world's resources on credit and either repay after improving or grab power and leave it at that.