Final answer:
Comcast changed their mind in 2008 due to market competition.
Step-by-step explanation:
The reason Comcast initially refused to provide a contract to BIG10 in 2006 and changed their mind in 2008 can be attributed to market competition. Comcast likely faced competition from other providers who were willing to offer a contract to BIG10, and to remain competitive and retain customers, Comcast eventually decided to provide a contract as well.