Apologies, as this reply wound up being way longer than I intended, but once I started, I kind of wanted to chase the stream of consciousness to completion...
I've always just been drawn the ocean. As a small kid, one of my earliest memories is going to the NY Museum of Natural History; I still remember being (kind of terrified) in the blue whale room and wanting my dad to pick me up so that I could see the sharks around the perimeter. That got me super interested in the ocean and sort of got cemented when the first picture I remember my dad drawing for me was the sperm whale/giant squid encounter. I replicated that picture an untold number of times as a kid...
Without much supervision as a young kid, I spent a lot of time just reading at the library. I gravitated to books about animals and wildlife. Saturday mornings, I'd get up early and watch Mutual of Omaha's Wild Kingdom. I remember the first time seeing the orcas in south america beaching to catch seals and I was enthralled.
Fast forward to my pre-teen years and I had gotten my first aquarium; 10 gallon from Petland Discounts. That very quickly led to a 20 gallon with oscars & firemouths. Around that time I got my first book on saltwater aquariums, which i read & reread dozens of times. I remember being enthralled with the hobby at this point; I'd ride my bike for MILES all around to visit any LFS I could find.
At some point the oscars got big, of course, and I graduated to a 55 gallon. Had that tank mostly through high school. Eventually they bred, which was cool, but wound up having to get rid of the tank and fish to go to college. Original intention was to go into marine biology, but didn't really do a great job making that happen (my university didn't even offer as a major). After a couple of years undeclared, decided to get a degree in marketing (which I have very few regrets about).
Started working at the local Petland Discounts in college, worked up to assistant manager (partially by maintaining the most profitable marine fish section in the company). Got my first saltwater tank at that time; another 55 gallon that I started because I wanted a pair of ocellaris clowns (had that tank up and running through several homes/iterations for almost a decade). After a couple of years, got sick of slinging hamsters and needed more time to finish school, so transitioned over to an amazing, dedicated aquarium store. Worked there for many years, and worked up to management there. Even after starting my career, continued working there a few days a week for a long time.
Got married, had a kid, got sick of winters and moved to Florida. Got another 'real job' and found another LFS where I could work nights/weekends. After a little bit, started another small reef tank for my son. That tank lived through several iterations and upgrades, eventually moving up to a 54 gallon corner that I shut down about 7 years ago. I'm only just coming back to the hobby now (literally this month) and picking up what I've missed in that time. Surprisingly, not that much and there's a remarkable amount of latin nomenclature still buried that I thought long forgotten...
So, why reef keeping? I guess I was just enamored with the ocean as a kid. That transitioned from interest to hobby to work and carried through the start of my career and most of my life. As an adult, reef keeping sort of just scratches all of my itches. Beyond the constant experimenting and learning, there's all of the plumbing/carpentry handiwork that I don't really get to use otherwise. I also love gardening & landscaping, which has its part to play too. In the end though, I think it's just the lifelong pull of the ocean that is bringing me back...