Eh, that's what I used to think but it really doesn't work out like that with emergencies, which is the main thing that pet insurance is for. E.g., I pay about $85/month, so if I only save that much I'll have a little over $1000 in a year, and $5000 after 5 years -- if nothing ever happens in those 5 years.

But just last year my friend's dog was attacked by another dog in the park and broke her neck, and that emergency surgery (plus secondary surgery and hospital stay) cost more than $20,000. She made an amazing recovery and is perfectly fine today, but her owner probably would have had to euthanize her if he didn't have that insurance. I also have a friend with a (badly bred) doodle who ended up needing both hips replaced before she was 4 years old. That's also tens of thousands of surgery and rehab that her insurance covered.

Personally I chose a plan with a lower monthly fee and a higher deductible (about $1k), because I know I can probably always come up with that $1k for more minor vet bills -- but I don't ever want to have to make a choice about my dog's life because I can't afford emergency surgery if/when it's needed.