The NCAA tournament rewards teams who have had successful regular seasons and have won their conference tournaments. They're in the money. The more you win, the more money you make.
Most coaches have tournament incentives built into their contracts.
Bonuses for getting their team to the tournament, and more money for advancing through each round. The wrong seed in a bracket can make a million dollar difference to the school and in turn, take money out of the coaches' pocket. The players of course, get nothing. The players are doing the work, getting the glory, and many times the blame, but none of the money. A college education for free is the payoff for many, and for only a few, a shot at professional basketball.