You may be conflating class and race (it's a common error). A neighborhood of wealthier, successful people (regardless of race) probably want their neighborhood to be a quieter, nice-looking, pleasant place.
I've lived in both HOA and non-HOA neighborhoods. If there's a barrier to entry such as price, then generally a more successful (and hopefully more refined) type of person will move in, and generally the homes will stay nice-looking without rules. Without that, then an HOA to try to maintain an aesthetic baseline can be very helpful. All the homeowners benefit from maintaining an attractive neighborhood, in that their home values will be higher.