In ancient Rome, involvement in politics was an unpaid opportunity. Why, then, were some people able to get involved in politics?

The rich (patricians) who need not worry about finances unlike the poor and the farmers (plebeians) of Ancient Rome, were able to participate in unpaid politics because of their wealth. They did not need to earn more money than they already had hence participated in politics as more of a hobby than source of income. For the poor this would have been a waste of time that could be spent farming or searching for work.