I had not previously checked out that link. From personal experience, I know that when I went to one of their houses for a tour, it was $20 or thereabouts, and from the crowds when I was there, I figured that maybe 1000 people were going in that day.
I sort of doubt people go there specifically because of the royals, weddings and funerals aside, but if you're in London you're probably going to something like the changing of the guards. And if you're near one of their other pads, anyway, you might as well have a look around.
I believe we went to the place where Anne spends most of her time, these days, can't recall the name. Interesting to find out that back in the day, whenever the king slept there, it was an honor to be invited into his bedroom to watch him fall asleep.
And people wonder how Trump was elected.