Oof, now that's a story that can be told in many ways.
Short & Simple: I never had the need to ride a bike, I never felt like I wanted to (when i was young), and no one ever decided to teach me. I lived on a 13th floor until I was 10, and after moving to the suburbs, I was already so in love in computers I still didn't care for it.
Longer: I was the prototypical shy and introvert nerd, living in his bubble. Early on I developed an eating disorder which made it so I could only eat very specific types of food, which further led me to be in controlled social environments (e.g. I rarely ate "at school" and always ate at home). Couple this with the fact that I was instantly a "computer, maths and science geek" and terrible at sports, there never was a need to ride a bike. I grew up in Coimbra, Portugal, and the city also isn't particularly prepared for bikes. My parents were also very protective of me when I was younger, and neither of them had a bike anymore, so there really was no reason for it.
Longest:
When I was very young I had some illness that prevented me from eating most food for a while. Somehow, after that passed, I developed an eating disorder whereby I was no longer physically and psychologically capable of eating most food. It wasn't the illness from before, it was something within me that would lead me to refuse to eat or to get physically ill at the thought of eating certain foods, like a phobia. I'm pretty sure if you look it up on the DSM it shows up as ARFID (Avoidant Restrictive Food Intake Disorder). To this day (I'm 29) I still struggle with it, although I have slowly managed to improve the situation (add stuff to my diet) to allow me to be in more social situations and accept my quirks (one such example is the fact I'm telling you this here knowing it will be etched on the internet permanently). To give an idea of the magnitude of the thing, most of my diet, up until I was 18, was baby food (and every kind of crappy assortment of chips/candy/crackers you can imagine). You read that right. If you're curious I can share more about that diet, but I doubt you are :)
This condition made me feel very uneasy in certain social moments, like school trips or lunches or even a simple dinner or going to the movies. Since I couldn't eat what other people ate, and what I ate was utterly weird and bizarre, I simply didn't go for fear of being mocked or looked down on.
I was also always the good grades guy wherever I went. I always came top of the class, even in college (where things were already starting to change for the better). This meant that, especially early on, I was always a bit isolated. I don't have any problems making friends or keeping them nowadays, and even then I always found friends and I was bizarrely a very sociable person (not the kind of "shy kid at the back", but the one that "gets out there and rallies against teachers if necessary"). It's just that most of my interests weren't the interests of my peers. I liked maths, coding, philosophy, psychology...and most of my friends and peers had other interests. I'm not saying my interests were better (far from it), they were just different.
All of this, coupled with somewhat protective parents, meant that even though I always had social groups (including family friends), I was never keen on "going out" and "partying", or "going camping". So I never wanted to learn how to ride a bike. There was one time when I was very young and we were on vacation at an aunt's house where I briefly tried for a little bit, and failed. But that was it.
Nowadays, while I am certainly still a "stay at home 99% of the time" kind of guy, I exercise, I like walks, I like hanging out with my friends once in a while. And, yes, I would like to ride a bike because it looks cool and awesome. I have an exercise/static bike at home and would very much like to pedal the real thing. Hopefully very soon I'll accept my friends' offer to teach me how to ride one.
You asked, I answered, sorry for the long reply :) If you have any questions, feel free to ask. I just really never felt like I wanted to ride a bike until I was embarrassingly old already. The first time I remember _wanting_ to learn was when I was 19!