Simple answer. It's so easy to practice.
Most who miss out on music think that "You have to start when you are young".
Not true. However young people have an advantage - more free time to practice. Jobs, family responsibilities leave little time for practice. No practice, no progress.
Enter the harmonica
You carry it in your pocket. You are always ready for practice.
Catching for a bus. Warming up a car. Waiting for a shop to open. Your day is full of practice opportunities. All you need is your instrument. Your harmonica
15 minutes practice a day is enough to learn quickly. Hard to find this time with other instruments. Easy with harmonica.
"this course gave me a new start"