Have the government pay for college tuition for all U.S. citizens

Every year thousands of students around the country pay a ridiculous amount of money to receive a college education, and spend a long time after paying off their debt. This system discourages many students from going to college; students that could be more successful and happy by going to college. The U.S. already pays about 10 times as much money on defense as it would if it payed for every student's tuition. Also, if this passes, the higher salaries earned by students who can now afford to go to college would raise the government's revenue from federal taxes and would actually be more than enough to pay back the government for its spending (i.e. the government would make money in the long run).