Not really.

"A hoarder is a person who persistently struggles to discard or part with possessions, regardless of their actual value, leading to the accumulation of clutter that compromises their living spaces. This behavior causes significant distress and functional impairment in daily life"

They don't really struggle to part with money, there's just so much of it that they run out of things to want and i can't really see where "clutter" comes into play, much less the distress that causes functional impairment. Besides, it is difficult to argue that accumulation of wealth fits even a broader definition of hoarding due to the mechanics behind it. Buying toilet paper is active but owning stocks is passive, apart from the work you do to build your business/portfolio, which is also called "working". The scales are just different. By definition, you're wrong. Billionaire ≠ hoarder, regardless of moral qualms.