If I am expert in subject A and know nothing about B, and someone else knows B and needs A, then we're in business. Even if they know C (heh), maybe I will need that in the future, we're still equals.
I've never encountered someone who had the right attitude and not had something to trade.
Your argument might come across a little selfish, but I wholeheartedly agree with you.
I've found that there are an enormous number of people out there who are really just looking for the quick fix and want it cheap (aka free). You'll invest and start explaining something to them and once they realize you're trying to show them how to do it themselves and that you aren't going to just do it for them, they quickly lose interest.
If they instead place some sort of value on the knowledge they want from you, and realize it isn't free (I.e. it will at least take some time and energy for them to apply), the more receptive they are.
I've never encountered someone who had the right attitude and not had something to trade.