Every circumstance is different. To make blanket statements of what people should or shouldn't do is, IMO, a blinkered view.
When my dog had his accident, we didn't have him insured. Please don't jump to the conclusion that we were in some way irresponsible or couldn't afford it; it was due to circumstances at the time, personal to us.
We were given the option to have our dog put to sleep or spend a lot of money to help him have the best chance possible. We chose to do the latter; as a result our dog is probably one of the most expensive dogs in christendom.
We went into debt, and I don't care; it was a choice we made, and one we deal with.
Other people I'm sure would say we were stupid, it's only a dog, have him put to sleep, you should have had insurance, whatever; thats fine, they are free to think what they like (I don't particularly appreciate it when they voice that opinion, but hey ho, again it's something we deal with).
I believe that as long as the best interests of the animal we have chosen to bring into our lives and care for (and thereby taking ultimate responsibity for them) are paramount in our minds when making these decisons, then others shouldn't judge, especially if they are unaware of all the circumstances.