I am a former mediocre runner turned colorado cat 2 cyclist. I stopped running in HS but never ran faster than 17:00. I will admit that maybe cycling is not as deep as running, surely fewer young people race bikes competitively than run track or xc. However, one major difference between cycling and running is that at any given cycling race (and there are at least as many as there are local 5k's etc), just about every entrant is training competitively and trying to race for the win. There are very few Joe-Middle of the Pack/back of the pack Gallowalker types in cycling. So the participation numbers are misleading a little bit.
One other consideration, unless you have raced either in California, Colorado or on in an NRC race you should not try to call yourself "nearly a pro" after just a bit of cycling. Mr. 6'0 145 lbs doing intervals at 330 watts... this is only 5 watts/kilo, I put out more watts as a cat 5 in my first year as an 18 year old...and I couldn't win a race. Many runners would indeed make decent climbers, but that's not what makes an excellent cyclist. You succeed based on your ability to hold high watts, AND produce 1000ish watts for short periods of time, or 500-600 for a minute at a time, and then recover when you go back to your 330 watt threshold. There are very few runners that could get on a bike and even produce 1 thousand watt effort.
Finally, if cycling has such a shallow competitive field why don't you jump in? There is significantly more money available in the sport of cycling than in running. I felt terrible as my roommate, a 14:10 5ker and 63 minute Half Marathoner gets to race a few times a year and if he is lucky brings home a couple hundred dollar paycheck when as a cat 4 I was brining home 500 bucks a weekend and then as a cat 2 I am racing for 1000's of dollars of prize money every weekend.
I understand the pride of running, all you need is a pair of shoes and a clean (?) pair of shorts and you are capable of being a self-made athlete. And sure, cycling has a high up-front capital cost; but, like any business venture the high upfront capital cost of cycling can pay greater dividends, and cost you less down the line. I have only purchased 1 bike in my time as a cyclist (others have come my way fortuitously), and spend perhaps $100 a year in maintenance. Every runner I know goes through 2 pairs of shoes every 3 months for a cost of ~$800/yr. My first bike was $1000, if you're sure of your potential success, cost should not be an obstacle.
I have great respect for runners. Many in your/our ranks have made successful switches over to cycling: Jonathan Garcia, Jason Donald, Amber Neben, Busche, etc. Admittedly these runners were not as elite in your playing field and I can only speak for myself, but I made the switch because my running was simply awful, my VO2 max is 75 so I ought to have been decent at running but it didn't work out. The bike worked out my efficiency issues and all the power my body could generate went straight to the pedals.
One final, admittedly circumstantial, fact to be considered. Zersenay Tadese was a moderately (to put it generously) successful cyclist before becoming arguably the most dominant running road racer of the past decade. Just because some of the tools in our toolbox overlap sports does not diminish the beauty of competition in sport or the other. In the end to be great at one or the other requires a different toolset.
Let's respect each other, do our best at what we choose to do and challenge each other to do better by showing up at the starting line rather than belittling each other on an internet forum. Another cyclist will have to toe the line on my behalf though, since I know the average letsrunner would leave me in their dust!