One of the recurring annoyances for people wanting to launch new projects, products, services and offerings is the vast number of people who think your stuff should be free.
Don't listen to them.
The same folks will be charging. You can count on that.
In this particular case, Nick codes solutions and teaches programming for people who then have high hourly rates.
Your "don't be so selfish, I just want to pick your brain" folks wouldn't expect to give their valuable stuff away, so why should you?
It's especially difficult for artists. For some reason, folks think because you derive pleasure out of an activity it means your landlord won't demand rent at the end of the month.
Remember people die from exposure every winter :)