This is just knee-jerk, spiteful cynicism. I know a number of people who dream of working for the U.N. and getting the job through connections certainly doesn't factor into it. Quite the contrary: landing a U.N. job (at least in the U.S.) is extremely difficult, and certainly far more difficult than other job opportunities available to these sorts of people. They're driven to the U.N. out of idealism, not laziness.
I think in some ways that's true, but then why does it seem to be so congealed and terrible? All of these idealists should make it better somehow no?
Maybe some (not all) of the people in higher positions get appointed through more political, less idealistic processes and gum up the works?
Maybe having an organization that by its very nature needs to cater to so many different world views means that it can't actually get anything done efficiently. Too many cooks in the kitchen.
For every idealist trying to make a difference, you get some bureaucrat from <insert country here> who is only interested in having a title and bilking it for as much money as it's worth. Because said bureaucrat is from <insert third world post colonial country here>, firing them in favour of <idealist overqualified candidate from the G7> is impossible, and actually contrary to the mission of getting various nations to buy into the system.
I used to really believe in the United Nations. Did MUN in high school, got a degree in politics, studied how developing polities can form ideal governments, the whole nine yards. Now I write python for one of the beltway bandits. At least the problems the computer has can be solved by logic and hard work.