Extended warranty
You think you are saving cash on the off chance the product you bought doesn't hold on and you need repairs, but I don't know anybody who has ever been happy about this choice
On the opposite end of the spectrum, car insurance for rental cars. My father and his colleagues used to travel the world and rent cars for several weeks at a time. It would only take one car accident in all those years of renting cars to justify the cost. Many of these rentals were for off-road use. The rookies thought to save cash passing on the insurance and would eventually shell out thousands on repair