People are confusing the role bonus with the daily tome bonus they are not the same thing. You will not get 7x more tomes if you play a tank. You get bonus exp and gil is the only thing you get from the role bonus. At level 50 that is currently 750 gil and 0 exp because you are capped.

So 750 gil x 7 = 5250 gil

That's it a 5250 gil bonus which isn't much gil at all.