In my (shared) experience, most insurance is no less a gamble than taking your bass out to a gig. I don't have mine insured because the cost of it balanced against the actual likelihood of a payout makes is pretty pointless (I have the basic MU insurance but that's free).
Insurnace is about minimising risk and, in truth, after 33 years of gigging with only one potential claim, I would consider gigging without insurance to be no grave risk. Sensible precautions such as making sure the instrument isn't too accessible to sticky fingers and, number one, never actually letting it out of your (or a trusted bandmate's) sight pretty much cover it.
I have little faith in insurance, anyway (after 11 years of insuring my dog, a recent claim, my first, resulted in a £320 bill being reduced to £200 - whoopee do.). They just wriggle out of it unless you are willing to let it take over your life and sepdn every waking hour chasing them.
As for venues where there is a likelihood of trouble, why would I play there anyway