Disagree. Just the other day I needed someone to replace my chimney cap. The quotes from the big companies ranged from $3k-10k. Utterly ridiculous. I got some guy from an app who bought the stainless steel cap for $300 and installed it for $300 more for a total of $600 and the work is fine.
Risk reward ratio is pretty good though. Insurance is just gambling for unlucky people.
You've got some weird math there in your ratio. At a minimum it's a giant hassle and can potentially bankrupt you in the extreme. Anything related with heights, electrical or water i would never risk hiring uninsured/unlicensed rando because the potential downside is essentially uncapped
The guys at the big companies have a service which tells them your salary and all kinds of personal details about you. The point is to see how much you can afford, pray on your ignorance, and milk you for as much as possible.