I always thought that Nole's family was fine off economically- they ran their restaurant when he was young and I always thought he was fairly comfortable.
Here in the US- you can say that individual's actions lack class regardless of their socio-economic background. And I don't think that the majority of posters who find fault with some of Nole's actions and that of his family are doing it as a class - or national- issue, but in fact because they may not think that everything he and they do is wonderful.
I am from a middle class background although my family became more firmly entrenched in middle class through the years as when I was little there were harder times with money. Both of my parents come from working class backgrounds, and their parents came from I guess what would be considered poverty.
Most tennis players I would imagine would have a bit of money behind them (before they became players)
If I recall correctly- I think there has has been some friction in Argentinian tennis because some of the players (Gaudio for one) do not come from well-to-do backgrounds and did not always get the support they needed from the country's tennis federation.