The job security is A Very Good Thing, and what I offer can be traded -- though I think I am already in "the best of all possible worlds."
Promotion? There's really nowhere else I want to go in such a large corporation; my position doesn't fit very well in any org chart and any way "up" is a long-term headache (called "manager").
They're still trying to figure out how to best use what I offer, while I'm shifting my offerings to avoid the most burdened roles. Got a wee bit trapped by this one but I am achieving the valued position of "Subject Matter Expert" (SME) and though I didn't ask for it I will have more "Subject Matter" to add. I've seen it before: when these guys retire, the loss is felt.
If you can do it, sion (and it looks like you CAN!) then go for it! I never found a job that could utilize what I had to offer in the way that would suit us all.
My supervisors were afraid I was after their jobs and tried to force me out of every job I ever had.
I didn’t want their jobs. I wanted to be their BOSS!!! LOL!
Good luck with what you are doing. I know you enjoy it, and therefore, you ARE irreplaceable!