Will simply buying a $5K bicycle allow you to compete alongside Lance Armstrong?
No, you would need to take steroids too.
But, in all seriousness, it is completely different than the diving experience - at least in my case. When I learned to bike, I was probably 5. I started with training wheels, then moved to my Dad holding on to the back of my seat. Gradually he started to let go more and more, first on grass, then on pavement. Eventually I got comfortable enough with it that I never needed him anymore.
With diving, I felt that I had rather intense training sessions, then it was like "okay, you're good to go now, bye". In the defense of the instructors, I was very skeptical of diving before I tried it. I've had a history of ear pressure problems, nausea and claustrophobia; which meant it took a lot for me to even try diving. To this day, I haven't logged more than 15 dives (sometimes I even wonder what I'm doing on Scubaboard), largely because I haven't gotten over my aforementioned issues.
To be honest, I don't LOVE diving. I happen to love to travel, mostly to tropical places, where diving is popular. I spent a month in the Philippines this year and managed to dive twice. The first, because I met a group of people who just got certified in Boracay and then asked me to join them. The second, because someone spotted a whale shark and I literally jumped up to find a shop who would take me out the next day. I feel that this is common with most people. They try it, but if they happen to do it after they're certified depends on all the stars aligning. They don't actively go out there and pursue getting more experience.
I used to teach skating lessons when I was in college. I asked to teach the adult classes, because I wasn't great with kids. I think 95% of my students were tourists or international students. They just wanted to try it because it's "the Canadian thing to do". They liked it - some more than others - but I guarantee that hardly any ever skated again. Why? Lack of access to facilities, the insane costs of gear, the fact that it's not common where they live...probably all reasons that can also be applied to the scuba industry.