This topic resonates with me. I find myself in that intersection of doing what I love, doing what I'm good at, and being reasonably compensated. In the past, I've worked in the intersection of only two of the circles (competency and compensation) and found I was miserable. I much prefer a career where all three circles intersect.
I'm probably an anomaly for this website. I don't install / sell IP cameras full time. I'm here because I enjoy the technology and this site allows me to stay immersed.
My current "what I love doing" job is working as a police officer. I ended up here after being dissuaded by my parents from law enforcement. Back then, I went after my second passion -- technology. I was always good at connecting car stereo system amps and equalizers. My school had a 32 terminal mini computer system and I hacked the factory account (the statute of limitations has long since tolled).
After graduating from college, and devoting 16 years to a career with EDS and smaller IT companies. I saw big changes in the IT support field and went through the "tech wreck" recession. I made the leap to passion number one, law enforcement, the place where all three circles came together for me.
It turns out that law enforcement is a big field with many specializations that no single person could ever master (evidence, case law, defensive tactics, investigations, armorer, motors, surveillance, etc.) I found myself being called into specialties requiring a technical aptitude: computer forensics, mobile computing, and remote surveillance. IP cameras quickly surfaced for me as the appropriate tool for surveillance as they allow for better resolutions, sophisticated integration, and remote live monitoring.
John mentioned, technology changes from generation to generation -- telegraph, telephone, wireless, computers, smartphone apps, etc. Miniaturization allows these cameras to exist; they are computers in an increasingly small box. They represent the next generation of technology, one of the places to where the technofiles will migrate.
I foresee home automation with remote monitoring as a growth area in the next decades and IP cameras will play a significant role. It could well be the next intersection of the three circles for me.