What were the cons in the Greeks going to war with Persia?

Answer 1

Persia had a strong record of defeating people and ruling them to organise peace and prosperity, through a strong army and navy, and the use of bribes to weaken those who tried to stand against them. This had worked with the Greek cities of Asia Minor now part of the Empire. The bribes were also working in mainland Greece, where the northern city-states had gone over to the Persians, and others were wavering, believed to have cut secret deals.

The southern Greek cities had to weigh up the risks, and wonder if their neighbours could be trusted. Fifteen years earlier, the rebelling Ionian cities had lost the decisive sea battle of Lade when the fleets of half of them left the battle site without engaging, their leaders having cut a deal with the Persians, and Persia established complete control of the cities in Asia. Now it was the turn of mainland Greece, and who would take the bribes, who could be relied on to stand firm? To cut a deal with Persia, or risk losing both a war and their negotiating power.