Have three challenge matches a day. After getting at least 20,000 seat stadiums a day, buy a bonus challenge and have four challenges per day. Get challenges from people with 250,000 seats. Although you will get the maximum amount of money earned per day, you will get a very high negative goal difference and have loses. Repeat this until you reach 120,000 stadium seats. After two or three days you will reach 250,000 stadium seats.