The problem with trying to learn carpet cleaning on YouTube is that you can learn a whole lot of very bad techniques and practises that you then apply to your customers carpets and get yourself into a whole lot of trouble.
I Know a guy, in fact quite a few guys who thought it was a good idea. It turns out they didn’t know the first thing about shrinkage and thought that it was the pile that shrinks, which is utterly bonkers.
My advice is to go on a proper recognised training course, or look for something else to do as a business.