The thing with doing one thing and well is that you are missing on all the other cool things in life. What if you chose the wrong thing? Why is being in the top 99th percentile so much better than being in the 90th percentile? Is it worth the extra 10 years spent working on that if you are still not in the 99.99th percentile? I don't think you should focus on the pay-off or the "OMG, I got so good at this!" part, you should just enjoy the journey and learning process. If you are ok with learning very slowly but always progressing it might be better than spending a tremendous effort in a short time just to quickly reach your ceiling and than hate the thing that you do.