Agreed, 10K hours is not enough to become an expert in coding for example. You need at least 40K hours with many different languages, companies and projects to

Agreed, 10K hours is not enough to become an expert in coding for example. You need at least 40K hours with many different languages, companies and projects to become a senior developer. I did 44K hours in 15 years working for around 15 different companies in 6 different countries and open source work on the side for nights and weekends before I became CTO of a small bootstrapped startup.