so i just done the maths (hopefully its correct ) but from what i found if you fully upgrade your gold gain it would take 14 years to make back the fsp used to pay for it which i personally feel is abit pointless.
i have my gold gain maxed at 505 an hour, 505 x 24 = 12,120 so thats 12,120 gold a day and in total it costs 250 fsp to max your gold gain. an average price for 1 fsp is approx 250k ... so 250 x 250,000 = 62,500,000 and if you divide that by 12,120 ( gold per day) you are left with the number 5156 (rounded down) so that means it will take approx 5156 day ( 14.12 years) to make your money back from the gold gain
what do you guys think about it ?