Billionaires are greedier than dragons. The richest greediest dragon in all of fiction is Smaug, and he has an obscene amount of wealth. I've seen estimates of his wealth ranging from 5 billion dollars of gold on the low end, all the way up to 15-20 billion dollars of gold on the high end.

However, Smaug is an incredible outlier. He's basically the Musk of Dragons. The absolute most gold you'll find on a dragon in any video game or ttrpg is 5 million gold pieces. That's only if RNGesus smiles on you, and rolls as high as it could. The average is more like 3.5 million gold pieces of wealth.

1 gold piece = ⅒oz of gold. So we are looking at 350,000 - 500,000 oz of gold for the upper 50% of all red elder worms. Any other dragon type doesn't hoard that much.

That comes out to a real world value of between $800,000,000 to $1,200,000,000. That's for the richest dragons out there.

Most dragons aren't billionaires.

Therefore, billionaires are literally greedier than the anthropomorphic caricaturization of greed from legend, namely dragons. The greediest fictional thing we could come up with isn't greedy enough to accurately portray these people's mental illnesses.