Okay, very interesting... I like the way you think. Luckily, I built various components and the entire CSS layer (which gets very complex) is really only understood by me... which is a nice monopoly from time to time. But yeah, if I leave I know I'll be forced to continue doing the same work but also forced to educate the entire team, etc. on my knowledge.
But you're right, I don't want to make anything personal, it's purely a business and career growth decision on my end. I love the company and what they stand for, but I don't like feeling like I'm being taken advantage of by being underpaid for my skill sets.
After working here for a while, I've noticed that the interviewees are lacking in skill sets and we can't seem to gain or retain top talent... which also leads me to think I have a leg-up on this as if I leave, they're screwed in certain areas.