One can only select from what is available. And that is where the luck comes in. But they barely select the cabinet, thier staff do all the work, they just have to pick from a short list that the current political climate provide as possible options (congress has to approve them). Their primary staff are either people who joined on long ago, or just the people the party has deemed are having the most success.

And while you think trump’s administration was ineffective, that is only true in the sense that he didn’t do what you wanted. From the conservative point of view, he knocked it out of the park. His administration used the pandemic to further drive the voters to extremes, which his party needs to gain power. The supreme court (also mostly luck). The plethora of conservative federal judges. The rich got richer and the poor got poorer. The list goes own.