If he can make that much money as an ex-president, I don't understand why we give him a salary. Sure, pay for security, but he can surely afford to pay for the rest of that stuff.
Maybe we should look into a maximum that the tax payers will pay (set to inflation) and cost over and above that the person themselves has to take on, and make it linked to what their income is.
Secret Service protection, which starting with GWB is only for 10 years, I have no problem with.