The problem with the "10,000 hours" principle is may be you will be immensely successful following it. But don't be surprised if you don't.
For you to be successful "10,000 hours" might be one of the many thing that need to fall in place. In many cases it might not even matter, to give you a simple example- If you are born in a society full of tribal wars in some poor country in Africa. I seriously doubt merely putting in 10,000 hours of work will help you out of the situation. The fact is luck, opportunity, being at the right place all matter.
i doubt anyone is claiming that having 10,000 hours put into a skill/craft is going to make you successful. It's merely a pre-requisite, and not the only one at that.
For you to be successful "10,000 hours" might be one of the many thing that need to fall in place. In many cases it might not even matter, to give you a simple example- If you are born in a society full of tribal wars in some poor country in Africa. I seriously doubt merely putting in 10,000 hours of work will help you out of the situation. The fact is luck, opportunity, being at the right place all matter.