How wealthy were most mafiosos in their heyday?

It's an interesting question. In this list only 2 of 8 are Americans - https://www.investopedia.com/financial-edge/0912/8-of-the-richest-gangsters-of-all-time.aspx

I read this book on Meyer Lansky. He didn't flaunt his wealth.

https://www.amazon.com/Little-Man-Meyer-Lansky-Gangster/dp/0316511684/ref=sr_1_3?crid=2O8BVZUUIPG69&keywords=meyer+lansky&qid=1581210271&sprefix=meyer+lansky%2Caps%2C362&sr=8-3

if you think about it, there were only a handful of mobsters of that era who were famous, so it would seem most of the others were possibly doing maybe a bit better than "just getting by." Think of Bobby "Bacala" or Silvio on the Sopranos. They never seemed to be "working class" mobsters.

And pardon me for going a bit off-topic, but...
This discussion reminded me of a discussion I tried to get going years ago on the IMDB boards about "cowboy money." I've always been fascinated by scenes in cowboy movies when they're gambling in some dinky saloon in a dusty little town. They bet hundreds of dollars, which always seemed way out of line, when you consider a meal might cost 25¢ and a new hat might be $2 or so. But I guess it would seem a little comical to see rough and tough gunslingers sweating over a $3 bet.