Yes but winning - particularly in sporting events - is generally a result of conditioning, training, and practice. You can win once, but if you don't continue that level of commitment, or if someone else puts in even more work, you can still lose.
Heck even with the same level of commitment from all sometimes you just age out of competitiveness. Assuming equal levels of work, you won't be as physically capable at 30 as compared to 25. In some sports and activities extra experience gained can balance out the slight decline in physical capability, but there will eventually come a tipping point when it won't.
A lot of people simply can't let go of that feeling of being the "Best" at something, even after they no longer are.