Regardless, it's bad practice. The coach is under contract to win - that should be enough. Booster programs should be assigned to provide help with concessions, hospitality areas, spirit packs (extra clothing), etc.
This is false. Football coaches are working 7 days a week from sun up to sun down. If they make it to the state championship, thats 5 extra weeks of work. During the summer, they are working close to 5 days a week. There is absolutely nothing wrong with giving coaches a little well earned incentive at the end of a very successful and tiresome football season.