"You" (collective rather than specific as I don't know what your situation is) are ptobably not as hard to replace. The company I work for has replaced people who are "highly trained, highly skilled" plenty of times. The fact that they're relatively highly paid means that they're first up for consideration when it comes to reducing the headcount in a situation where we still need feet on the ground.
Unless you're in a position where you'd be making more as a consultant (in which case... why aren't you?) you're likely not to be as irreplacable as you think.
The big difference between myself and those guys? I'm in a Union, I have the legal protection that offers me, I make it known that I know my employment rights (because I have a team of experts who I can call upon to answer questions if I'm unsure), and that I don't have to be able to afford to outlast them in court if they get rid of me without following the proper proceedures (which mean I'll come out of it with a lot of money anyway) since I've got union backing.
What do I pay my money for? It's like having lawyers on retainer. In fact, it's not just like having lawyers on retainer; it is having lawyers on retainer. (I just share the cost with a whole bunch of other people)
I won't be striking, because they don't happen to be the recognised union at my place of work (but if they were then I'd be quite pleased about it), but the lawyers are worth every penny.
That's just the selfish part of the equation.