The reasons for Colt being pushed out of the da revolver market were complex and they took place over a 30 year span of time.
Their union labor costs were bankrupting the company
This was never true. Labor costs though were one aspect of the problems.
Colt was greatly mis-managed over several decades and the story is a painful one full of bad decisions one after another.
Bottom line is that Colt lost the law enforcement wheelgun market in the post war period to S&W and Ruger.
A few years ago when they were still making Pythons, Anacondas, etc. the guns were not selling. For $400. less than a Colt a fella could get a new Ruger, and that's what people did.