I clarified this out on the housing forums for an individual who felt the same way. People are missing the point that gil has different weighted values from server to server. Because you have way more players, you generate way more gil and have way more overall gil, the value of gil on each server is very different. Its like going to another country and having your currency swapped for theirs. It would be much easier on the average person if we named our currencies differently. For example, yours can be called gil and our server we'll call it yen.
1,000 gil on your server is equal to 10 yen on ours.
This helps an average person to differentiate that 1000 gil on your server = 10 gil on our server but because we call it all gil thru out all the worlds, the average person believes gil has the same weighted value thru out all the servers. Which is false.
The variations, of FC-lots being bought, we see in each of the population ranges is directly related to the attitude of the population. For example, we have 3 large servers, labeled as [A] [B] [C] with equal number of players. In server [A] 75% of population constantly generates gil, server [B] 50% of the population constantly generates gil and in server [C] only 25% of the population generates gil. The more gil generated on a server, the higher the likely hood more gil gets in to circulation a.K.a gil thru the market board. Obviously server [A] will easily reach the gil sinks before server [B] and server [C]. This is why we see some servers doing way better then others in the same brackets. Its even possible that some servers have come to a complete halt because their population completely refuses to generate any gil or do anything. They prefer not to work for their lots but pout in hopes of extreme price drops to pre 2.1 overall gil/circulation values. This hurts the overall population for that server.
This is why we see variations in the same brackets. Each server, in the same brackets, has the choice to produce the same amount gil but because its a choice, people can choose to do or not do it.