I've had GM extended warranties and they've been excellent. I had one extended warranty that was an insurance plan and they declared bankruptcy.
I put lot's of miles on my vehicles and they receive hard service and also good maintenance.
But I've still made claims on extended warranty.
Modern vehicles have an awful lot of electronics and electronics are expensive to fix.
Modern vehicles are also very expensive to repair....in every aspect of the powertrain.
I also like to fix my costs, I don't want any big $$$$ surprises. The extended warranty does 'fix' my repair costs.
Also I like the peace of mind aspect.
On some vehicles, my claims didn't exceed the additional cost of the extended warranty...on other vehicles it did. Sometimes you eat the bear, sometimes the bear eats you. But at least when the bear eats you, you limit the damage by having the extended warranty cover the costs.
To me it's worthwhile.