I think it was about coveting power. The Roy kids didn’t care about money. They didn’t want the big payday. To them money was just a number—one of Logan’s mantras. They coveted power.
Tom definitely coveted money at first. But by the end he coveted power as well. He could have easily accepted Shiv’s invitation in the finale to have a normal marriage and live the life of a billionaire. If all he wanted was money, that would have been an easy yes. At that point he wanted power.
It is a good question whether the show creators believed that unlimited money leads this corruption of the soul. Like I said before, there isn’t a counterfactual juxtaposed against them in the show. It did seem like Josh Aranson was pretty well rounded and a family guy…we just don’t know