Lets see...
Kenny did the hijacking because of all the strikes...he gets the money and stays for decades with a job he hated. I guess he stayed not to draw attention since he looks so much like Cooper
Rackstraw appears to be upset that his military career took a dive..as 377 mentioned, he tried to make it look like he drowned but it failed, so he wrote a letter taunting them...
Weber gave up trying to get away with petty crimes and "jumped' right into the hijacking with success...his background makes perfect sense...worked at area 51, most likely was in the grassy knoll, knew every suspect that comes into play, was a CIA operative, built radio towers, paved the first 100 miles of route 66, BBQ grills were named after him, did the engineering on parting of the seas, was a well known and respected parachute rigger, knows exactly what happened to Hoffa, Earhart, and Waldo
HE WAS.....THE MOST INTERESTING MAN IN THE WORLD.....
...