People are talking about taxes, but there is one part that is overlooked in how the decisions were being made.
College in the USA used to be much cheaper. The federal government gave state governments land to sell in order to fund "land grant colleges", basically the top of most states' public education system. There was massive funding into these colleges, which generally meant that private colleges needed to be somewhat competitive with poorer students. Government funding continued through the middle of the twentieth century with the GI Bill and a mix of federal and state aid to keep tuition low.
However, starting in the 1990's, three things started happening. First, millennials were getting ready to go to college in a wave that colleges had never seen, requiring the building of new facilities. Second, school rankings were becoming more important, so colleges started chasing clout and that chase cost money. Third, financial aid started to incorporate student loans as a way for kids to pay for college.
So, tuition costs soared as colleges were spending massive amounts of money on new buildings and ways to increase prestige while aid programs shifted to loans. In a lot of cases, states even pulled back funding as student loans could fill the void. Students still came as it was seen that a college education was required to have a good middle class life in the future.
Now that the millennial wave has crested, colleges are dealing with massively falling student numbers, which is a major problem given it became a significant revenue source.