Wealthy absent G5:
Collect 5M from your filled bucket
Just to clarify, you have to collect 5M from your bucket, the bucket doesn't necessarily have to be full.
In order to get your bucket to hold 5M you'll need to upgrade it in the "Political Investments". Not only can you upgrade the capacity of your bucket, you can also upgrade the rate in which you bucket fills up. So the faster the rate your bucket fills, the faster it'll get to 5M for the achievement.