One who withholds grain will be cursed by the nation (Proverbs 11:26).
This verse refers to people who have knowledge and refuse to share it with others. Our Sages strongly criticize these people. The Talmud states that prophets who did not convey their prophecies to the people committed a grave sin. The Sages extend this principle to one who has gained insights into the Torah and does not make them available to others.
This principle applies to skills and talents. In the Sanctuary, those Kohanim (priests) who possessed certain talents were soundly condemned if they guarded them as family secrets.
Exclusive economic rights such as patents and copyrights pose no problem; inventors and authors should enjoy the profits of their labor. However, when the question is not one of income, but merely one of pride in being the sole person to possess information that others could use and enjoy, the Talmud spares no words in its condemnation.
We pray to God to grant us wisdom, and if we possess a particular skill, we should recognize it as a Divine gift. We should be grateful for having been chosen as the recipient of this gift, and so we should never be selfish and claim this gift as our exclusive property. Rather, we should make our talents and knowledge available to everyone.
To the degree that people can teach, they are obligated to do so, regardless of their status in life. If others fail to take advantage of what a teacher has to offer, that is their misfortune.