I have been wondering about that. I think it is because for people like me, with spare cash, the cost of the royal family is insignificant to me personally. So I may as well have them for that feeling of Britishness, history and continuity and the entertainment, the pomp and ceremony, the 'indefinable something' associated with one of them turning up to open a library, I know that they as individuals are no different to me, but the idea of royalty has something, I couldn't say what as its all made up.
But in short they do me no harm so I cant get worked up about it, and actually enjoy it all. I am also aware that even without any public purse they would still be rich, and for the next generation at least news worthy so we may as well make use of them. I don't have a problem with inherited wealth. Why I make my kids life easier if I have the means.
The people who generally cannot afford them, well they have bigger things to worry about than being annoyed by the royals, its too far away. So they haven't the luxury of getting pissed off, or at least of getting pissed off enough to make a noise about it.
Which means that the job of being outraged by the monarchy is left to a few people who have the time, money and energy available to them to give it enough thought to be annoyed, but not enough to really be not bothered, or worse worried that pulling down the established rules would leave them worse off than keeping the status quo of monarchy, and the principle of hereditary leg up's being preferable.
I haven't the interest in being bothered on the behalf of others, as I do enough, I pay taxes, I am an employer of both skilled and unskilled workers, I volunteer, I donate. I already help society quite a bit and I think pulling down the monarchy would not make a jot of difference to those who could do with a bit of support.
Sorry, might be a waffle, lots of words, when a few would probably work better, but its been a long day.