As long as you don't fly openly in the face of society, society doesn't ask any inconvenient questions; and it makes precious short work of the cads who do. There are no secrets better kept than the secrets everybody guesses.
A monopoly granted either to an individual or to a trading company has the same effect as a secret in trade or manufactures. The monopolists, by keeping the market constantly understocked, by never fully supplying the effectual demand, sell their commodities much above the natural price, and raise their emoluments, whether they consist in wages or profit, greatly above their natural rate.
There was a time when people accepted magical experiences as natural. There were no priests then, and no one went chasing after the secrets of the occult.