Gaia Gold is certainly NOT difficult to obtain. The amount of gold a person makes depends on the effort put in to acquire said amount. If you wanted 10m really badly, you'll have to work for it. It certainly can be made within a month of medium effort.
If Gaia Gold were easier to obtain, then all the items on Gaia would inflate proportionally. If it takes 600k to buy a Chyaku Norisu Scarf, and then gold was twice as easy to obtain, then the Chyaku Norisu Scarf would inflate to 1.2m in value. The fact that a person can make 1M with medium effort within a day shows the excessive amount of gold being distributed.