> 1. I don't care about "upward mobility".
Wait long enough and you'll probably find younger people will do your job for cheaper, unless you can prove you're worth promoting. Some people can really stick it out, but usually by job security ("Larry is the only one who knows AIX and we can't replace it")
> 2. People don't see me as a threat to theirs
Eventually there will be layoffs, at which point you don't want to be the one guy that nobody wants around.
I know most people in tech seem to think they'll be employable forever, but it's an illusion.