Toxteth,
Fair point, in purely monetary terms you may well be >30k better off, however, and just trying to present a balanced arguement, rather than a pŁ$$ing contest...
If you retire at 55 and invest the extra 25% into savings, an annual net return of 5% will give you approx 25k over the 10 years. I still would suggest that the money is more use to most people while they are 55-65, rather than waiting till age 65 before getting the money.
Most people can expect to be still relatively fit and healthy when they retire from the military, the same cannot be guraranteed 10 years after retirement. It is a gamble.