Are you saying you can't fault someone for choosing to dedicate their life to personal power and profit over helping people or dedicating themselves to some morality besides greed and money?
Which distinguishes your stance her from Ayn Rand then?
Ultimately its a personal choice. As long as they weren't breaking any rules or law then there's absolutely nothing wrong with it. Same applies to Carter - its a personal choice he made. Most politicians who are in office for any number of years are confronted with loads of business and speaking opportunities when they finish up with politics, so its up to them whether or not to go in that direction or in some cases where they are older, simply retire.