My earnings have increased about the same in the last two years and "I have a great job, an unlimited potential, not bounded by a development environment that you have to justify every time you mention its name." AND I didn't have to spend 9 months of my own time learning something new.
The point is that everyone's situation is different, some people need to move on if their situation warrants it, others do not. It's not even that one language is more powerful, scalable, robust etc. its that you can meet the customers demands and MOST languages can do that. You obviously have a great situation where you are, and that's great, I'm sincerely happy for you.
But let me ask this: if something major/significant happens where you are, are you prepared?
Now, odds are, you'll be able to stay at your place for as long as you want, and that's great. Actually, that's fantastic. But many aren't so fortunate, and have to do some career planning. I'm serious and sincere when I say this - there are some people who should be hoping that they'll be able to stay in Fox for a very long time and it sounds like you fall into that category. That's not a value judgement, it's an observation, and I'd be surprised if you disagreed with me.