How did Gulliver become a source of income for his master in Brobdingnag?

As word of Gulliver spreads throughout the kingdom, the farmer begins to realize that there is profit to be made and takes Gulliver to the marketplace, where he performs shows for paying patrons. The show is so successful that the farmer decides to take Gulliver on a tour of the kingdom. Gulliver does ten shows a day, which makes him quite tired.