There's loads of family businesses that are perpetuated by siblings
Actually there aren't that many that get past 3 generations, the adage being that it takes one to build it, one to live off it and one to lose it. I think if you check it out you will find that is pretty often the case, although I would concede there are exceptions that prove the rule.
The stuff they do is just part of what's expected of you as a member of the family.
What behaving boorishly, feathering their own nest, breaking their own rules etc etc??
the main reason people grumble about the Royal's comes down to money
Actually you've got that back to front, its the main argument people come up with for retaining them, i.e. the tourist income blah blah blah.
The main people "grumble" about them is that they are an anachronism, which should have been consigned to history alongside such things as ducking stools, stocks, floggings and prima nocta. They are also the pinnicle of the class system, and as such we will never move past that thing which determines the vast majority of peoples life chances still to this day while they are still in place. Sorry to disagree, but financial issues are a minor distraction alongside those.