I've never had dog insurance. Always had a dog tho, sometimes two. At the mo I have my fourth dog, a lovely labradoodle. All my dogs have lived till old age. Whenever I needed treatment from the Vet, I paid for it. But I have never needed very expensive treatment, one labrador had an allergy for many years.
In short, if I had paid pet insurance for all those fourty years - it would have cost me a fortune. Better to save your money in a savings account, and it is there when and if you need it.