I bought three toilets when I bought my house, because the ones there were here didn't work. My in-laws bought a few toilets a couple years ago because theirs sprung a leak in the tank that was unfixable. Also, the water company gave rebates if you switched out your old one for a new efficient one.

I assume a lot of people buy toilets every day, otherwise Home Depot wouldn't have an entire aisle dedicated to them...