10 years to achieve true mastery? Sounds about right. I've also often said it takes 3 years to "get dangerous," in both senses. My data is from studying and teaching music.
On an even shorter time frame: once you get to the point that you're enjoying what you're doing, the only one who can stop you is yourself.
On an even shorter time frame: once you get to the point that you're enjoying what you're doing, the only one who can stop you is yourself.