This server needs more moneysinks. Adding prestiges will make players have a reason to spend their money. The attached file shows the price development from Default to Prestige++++ and continues the formula up to Prestige10.
A Prestige 5 is planned to be released alongside the Guardian Boss which we have been coding. We don't really think adding anything past prestige 5 would make sense but we have a few ideas on how we can make a money sink with ranks.