The term “bread and circuses” is used to describe the idea of buying public popularity by providing materials and entertainment. The history that I’ve heard is that this originally came from Rome, where politicians bought public votes with free wheat and public spectacles.
So, is that basically true, and if yes, what were the economics of this? Someone has to pay for the wheat and entertainment, so I assume that public office brought in more money than it cost to do this. Where did that money come from? Taxes, war booty, preferential trade?
The city of Rome, and really the province of Italy, during the Roman empire was a massive money sink. Money from conquest and taxes from the rest of the empire all came into the city, where it was spent on grain subsidy, public works, and entertainment. Meanwhile, Italy itself was exempt from taxes (until Diocletian in 290, Rome itself until Galerius, which is what led to their rebellion under Maxentius).
So the money came from the rest of the empire.
the Roman province of Egypt was at the time a major grain exporter, and they exported it as tribute to the imperial government. If the government wanted to hand it out in Rome for free or for a subsidized price, then that’s what they would do.
Grabbing Egypt is basically how the empire’s founder Augustus got so wealthy and popular. Before Augustus the wealth from Egyptian agricultural economy similarly kept the Ptolemaic dynasty in the black and very popular all over the place, since they could freely spend on foreign military adventures, Library of Alexandria, public buildings dedicated to their own names and similar projects.
Now before they got Egypt they would have had to get money looting other places. E.g. Julius Ceasar looted Gaul. Others looted Greece in early 2nd century BC, some decades after the end of 2nd Punic War.
Lots of slaves in ancient Rome, slaves don’t get freebies.