My heavily biased opinions:
Everyone is replaceable. Usually much easier than anyone can imagine themselves to be.
I can't see any negative in people receiving more education. I commend your boss for seeing value in investing in his people. The issue isn't whether it is worth it, but how to do it such that it is worth it.
What you should be asking for is your boss to invest in you as well, and send you to training. Maybe a higher level class.
Why do you really care? You need to be honest with yourself about this. I don't know you, your boss, or the other chaps ..... so this is by no means a judgement. But I would say based on what little we know, you are the Alpha dog in the group when it comes to the technical problems. You are probably in a position where you yourself determine (in one fashion or another) how much hands on the other guys get. They may just defer to you out of respect, or because they know you will get it done quicker. Because your the Alpha, the people aksing for help probably seek you out first, as human nature would dictate. The downside of course is, the rest of the group then never get any better.
In your position, what really should happen is that you should only get involved once the others have tried and get stuck. Then they come to you for help. Your in a position to teach them. I have seen many people in your position with the opposite mentality. They want to keep all the knowledge for themselves. I guarantee though that teaching them more only makes you stronger. Let them struggle on their own, and then when the ask for help, come in an assist. Show them what you would do. Explain to them why you are doing it that way, etc. But don't do it for them. Let them learn. If you're concerned about how fixes are made, or how the files are backed up, then you are in the position to train them as you see fit.
You can't fake interest obviously, and you've got to where you are because you had genuine interest whereas the others may just have interest in what they perceive to be the economic benefits. It is difficult to learn something, even simple things, without any genuine interest. It is ultimately why we end up with the careers that we have. But often the level of interest might wane because of distractions. Some of these guys might just be so overwhelmed with what they have going on already, that this just isn't high on their list. If you put them in a position where they need to use these skills once in a while, then maybe their interest raises in proportion. The interest also might not be there quite simply because they percieve a glass ceiling in the sense that no matter what they learn, there is not point because you will end up neing the one that does all that stuff anyway.
