AFAIK the games and races were free to attend, and were sponsored by the wealthy (especially the emperor) as a sop to the crowds. There was even a government of

AFAIK the games and races were free to attend, and were sponsored by the wealthy (especially the emperor) as a sop to the crowds. There was even a government office (quaestor iirc), whose job was essentially only to sponsor public games - holding the office was an important step in building your public image in the city, but also often meant borrowing incredible sums from even wealthier patrons. This is partly why Julius Caesar spent most of his career deeply in debt, for example.