Although these kinds of events can be quite interesting and arouse public curiosity, the intensiveness of training at one-time lectures is minimal since they are of more of an introduction to the phenomenon. They are to be considered a success if at least half the audience decides to simply attempt what they had been told about.
Unless you’re giving a free lecture to popularize the phenomenon or advertise a paid seminar, quite impressive sums are to be had giving talks to large groups, even if the cost of admission is relatively low and even after large expenses such as advertising, auditorium rental, and paying helpers (who are indispensable in case of audiences of 50 or more) are factored in. Let’s do the math: if you’re able to bring in 500 people at an admission price of 5% the average local monthly income, you’ll gross 25 times the latter figure. If even half that amount is spent on expenses and taxes, the net profit for one day’s work as an instructor will still amount to the yearly earnings for the man-in-the-street in that town. Meanwhile, 500 people will become potential practitioners, and many thousands more will learn about the phenomenon second-hand. As you can see, it’s worth a gamble – the risk of investing in the venture is justifiable.