The problem lies also in the ridiculous easy vanilla economy.
Very True, but it will be fixed, that is for certain.
Edit:
My results from Carthage:
1. Rebel Navies need to be weakened, You do not know how many times my fleets got wiped out by the rebels. I lost Sicily because of those damn rebels!!! I had an army of 5 Liby Poeni infantry, 4 long shields, 4 skirmishers and 2 war elephants on fleet headed towards sicily to relieve one of my towns under siege by the brutii and it got sunk by a rebel navy and I lost my faction leader because the reinforcements never made it. To make matter worse, when I saw the island was lost, I evacuated the troops from my two remaining settlements and you know what happened, rebel fleet sunk the boats they were in, and I had the advantage!
2. Carthage is wealthy, which offset the losses I sustained from sicily here is the screenshot of their financial status at turn 20:
Other than that no bugs, so far so good, though rebel fleets need balancing