A few reasons...
There’s no exclusion for stupidity. In insurance, if it’s not specifically excluded, it must be included in the coverage.
Secondly, actuaries have done the math (and they’re way better at math than you and me) and as long as you have paid your premium, and their settlement is less than policy limits, they make money every single time (in the long run)
Last, a bunch of bad publicity that might arise from “So and So Insurance Company didn’t pay my claim” is bad for business. And as stated above, as long as they settle for policy limits, they’re not going to lose money in the long run.
FYI, I own an insurance company holding several licenses, including an adjuster license.