Please start referring to billionaires as hoarders. It's more descriptive because the amount they have is never going to represent what they actually think of themselves. The whole point is they need an external locus for identity. Need. It's pathological.
I consider them akin to alcoholics; instead of seeking alcohol, they seek money and power. Like the alcoholic, some is never enough. They are attempting to fill an emotional void within their souls. All of them are deeply flawed people with flawed morals and values.
marauders, more likely
This is an excellent qualifier to add, it is important to let others know the foundation is hoarding. It's important to label it as hoarding as it highlights their weakness, not something that others may see as a strength (🤮). Marauding is a great descriptive word for the trauma they create.