Why Is Illinois Football Always So Bad?

I've always thought Illinois was a sleeping giant in Big Ten football, if not the in all of college football. They are the only major conference large state school in Illinois. Chicagoland is a recruiting gold mine. Northwestern and Notre Dame have more difficult academic requirements. If Ohio State can dominate Ohio and create a program that is always good, why can't Illinois do the same? How is it that Illinois can never get it right?