The Wealthy are a voter group.
Wealthy people are naturally very concerned about financial matters; they oppose taxes and socialism at every turn while supporting any policy which leads to them having to pay less.
In Democracy 3, wealthy people aren't predisposed to any other voter groups.
When middle earnings rise above average, middle income earners will begin rising into wealth, increasing the number of wealthy people. When high earnings fall below average, wealthy people will begin fall into the middle class, decreasing their numbers.
As can be expected, wealthy people get along very well with capitalists and have a historical blood feud with socialists and the poor. Middle income earners also get along very well with the wealthy, fighting for the same tax issues as them.
Wealthy citizens, especially Retired ones, may join the peaceful Heritage Society. Others, especially Capitalists who are dissatisfied with a nation's socialist policies, may end up joining the violent Battenburg Group.