Great question, OP. Complex for some to answer... I was drawn to diving later in life than I would have liked. There are so many reasons to love it...
It is therapeutic and cathartic. This runs deep with me.
Exploratory. Educational and mind-opening... Raising your empathy for other humans, animals, and the earth.
It can be as intellectual as you make it. Diving requires attention to detail, planning, your interaction with mechanical and (sometimes digital) technology, study of physics and physiology, and a certain amount of danger must be accepted for dives beyond maybe 30 or 40ft (10-13m). All of that only increases the farther down the rabbit hole you go... And I will go as far as I possibly can.
Also, for me, diving in general is MY thing... No one in my family does it and I love that. In fact, they are all scared of it. I love that even more. I can get away from everyone and everything and let the water envelope me.
I liked diving when I first found it. But I started to love it when I discovered what "tech" diving is. That's right up my alley. I'm not there yet, but I can't wait to cave dive (primarily). I really love seeing wildlife and reefs, but I need to be challenged. I'm going into the earth's black holes.
I do also want to see the great wrecks before they fade away... U869, the Doria, Truk, Scapa Flow, and
@Marie13 and
@Tracy 's Great Lakes wrecks (they'll be there for awhile), etc.
So for me, cave and tech wreck diving is what I dream about (literally).