cats

I will say that over the lifetime of my two cats so far (one died last August, the other is now 13y old), the insurance paid less than if I had just saved up the money and paid it myself, and by quite a margin.

It depends on whether you can do that, however. On average you'll save money by paying it yourself, but you need to be in a situation where you can have the cushion of money around to finance cat surgeries and dental work and so on.