The reluctance to give up resources also an understandable aspect of human nature, but power concentration in the hands of the few is always problematic. I'm very much a capitalist but the last few decades have persuaded me that wealth taxes are a necessary and moral correction to capitalism's unfortunate spiraling acceleration of inequality.
For instance: marketplace competition requires some regulation, but recognizing that regulation is a necessary evil with many opportunities for abuse (e.g. regulatory capture) helps inoculate against socialism's worst excesses.