No offense to your sister, but I really wish profits from REIT or folks with multiple rentals were taxed 90+%, or at least progressively increase rate with each additional rental beyond.
Here's the thing, they're not profiting much at all, if any. The whole group believes RE can only go up, so when the value of the home increases, they yank out all the equity and dump it into another property. AirBNB just keeps them afloat.
And a bunch of people doing that means that the property prices keep going up. Nice self-reinforcing cycle - while it works. Once it fails, though, there's going to be panic selling as all those people get wiped out.
