The point of becoming the global hegemon is much like that of establishing a monopoly, it is never having to compete again. That is after all the ultimate goal of every capitalist. It is only logical that once a capitalist achieves a monopoly they will use all means at their disposal offered to them by their position of dominance to prevent any new competition that could pose a threat to their position from arising. This isn't pathetic and any rational actor in their position would do the same.

The point as we Marxists always say is not that the individuals in positions of power in capitalism are morally deficient (i mean they are, but that's not the point...and whether that's because being in their position made them that way or because you only get to that position by being morally deficient is a bit of a chicken-and-egg question), it's that the entire system is built in such a way as to incentivize and produce these sorts of behaviors.

As such the solution isn't to simply switch out the leaders for less "pathetic" ones, it's to topple the entire system of capitalist imperialism altogether.