Technology

I wouldn't be surprised if at this point with the prices they charge, most of Adobe's users are either working somewhere that has it, or are students who want to work professionally with it, or are people in between jobs who need to keep up skills in it for when they can go back to work. Most anyone I talk to who isn't doing things professionally and doesn't plan to go professional will use something like Gimp instead of Photoshop if cost is an issue.

Outside of this though there's also just the fact that it being the industry standard does tend to cause non-professionals to use it too. Whether it be because they view it as better then the alternatives, or they want to get experience in case they ever want to use it professionally, or they just haven't heard of anything else and the tutorials they were able to find for what they wanted to do used Adobe products.

Either way though I bet that the majority of the money Adobe makes is from companies buying tons of pro licenses rather than from individual people using it.