Because it was never about the money. A man of Cooper's intelligence would understand that the FBI would record the serial numbers. He probably got rid of it...or at least hid it somewhere safe, maybe buried it. It was about the experience itself, to prove he could do it, and get away with it. He succeeded. He effectively beat the FBI. How many people can say they've done that not many.
https://katu.com/news/local/50-years-ago-this-week-db-cooper-jumped-in-history-and-mystery 50 years ago today!
Wait a minute He was in the military so probably has parachuting experience And he worked on planes so he would know all about those aft stairs. Holy hell Case solved
So I was at Easter dinner with my best friends family today, and their father (one of my mentors) claims that his brother was D.B. Cooper. I was obviously hesitant at first, and we didn't get too deep into it, but he has some substantial evidence.. the main thing that is keeping me doubtful is that the FBI was aware that he should be a suspect. Idk. I'm going to dig a bit more and maybe swing by there on a non-holiday so we can discuss more of the specifics.