Competitors burn the rounds really fast. Say you shoot a match every weekend, and you practice once a week, you can easily burn 300-500 per week. Competition is addictive. You will work hard for each additional point. You will let your yard landscaping suffer, you will leave your guitars collecting dust, you forget about television, movies, ballgames. Your eat, drink and sleep shooting.
Heaven help you if you start winning in your classification. You start striving to earn the next classification, and the next one after that. You start traveling to bigger matches. more shooting. More and faster reloading presses appear on the tables in the garage where you don't even pull the car in anymore. Powder starts coming to the house two or four kegs at a time.
From a local gun instructor's newsletter; he has an M&P Full-size 9mm with 10,000 rounds through it.