If my child wants to be a billionaire, should I say "Sweetie, you probably won't be a billionaire, so don't get your hopes up." Or should I say "it'll be tough, almost impossible, you'll need to work hard, study hard, be smart, etc."? I know which lesson I'd prefer to give.
It's fine to strive to achieve as much as possible and earn a bunch of money, but the core of the issue highlighted by that quote about "temporarily embarrassed millionaires" is a sort of class-affinity with the rich that is unwarranted for most people.
Likewise for the very poor. I hope to never be very poor, but I still wouldn't vote for systems that mistreat or exploit them. This is not because I'm trying to protect myself in the circumstances that I become destitute, but because I think morality requires the consistent application of principles to people regardless of their economic wealth.