What do you think the incentive would/should be for people to spend time and energy to obtain knowledge and information if there was no way for them to earn a living doing so?
Discussion
Be the first mover
Experts have knowledge which is based on (freely available?) information and own experience. The typical way is not to sell information only but help to apply it.
For example I am working as a consultant in the innovation field. I have published numerous books in my field of work. The information is almost free (the price of the books is hardly a barrier), I recorded hundreds of podcast episodes giving free stuff to everybody who wants to listen. And yet people book me to apply my knowledge and help them, even if they could learn everything themselves. But this takes time, I can do it quicker and probably better.
So my take is that the "sell information" business model is a difficult one. It might work, but it is always easier to protect a business model, when it is not only based on withholding information.