Great advice in general but...

People will steal your work and your products. You’ll find your premium digital products sitting for download on forums and it will break your heart.

Are these products GPL licensed? Because if I buy a premium theme and decide to give it away to people for free, that's not stealing... stealing is illegal and theft. When I buy a GPL licensed product, I can resell it if I like, and if you think it is stealing then it shows a misunderstanding of the license you are using.

Of course I understand the debate around this, but that is the GPL and WordPress is built around that, as such perhaps you could have phrased things better?