I can't speak for those who've had many lucid dreams, but I can speak for those who struggle to have them. The answer to why some people can't have lucid dreams after many attempts is we simply don't know. Just as we don't know why others can have them easier. I had a few lucid dreams in the past without even trying, yet many times when I did try, I was empty-handed. What are the factors that seem to separate the desperate from the proficient? It's a study in progress.

So, no one can tell you why you haven't had lucid dreams in the past. They can only give recommendations. I wouldn't stress out about it, as hard as that might sound. Part of the battle is mental. Either you'll have a lucid dream, or you won't, but at least you can try every time you go to sleep. For people in your case, I advise to use whatever aids you can find. Supplements, audio inductions, hypnosis, the works. My guess to how you'll get hundreds of lucid dreams is through experience. And the challenge lies in how you'll get your foot in the door, and the rest will be easy.