I once heard Waylon tell the story of that night; He said there was one seat left on the plane. Waylon and Buddy flipped a coin. Buddy got the plane seat. Buddy said (sarcastically) "I hope you freeze on that bus" and Waylon said (sarcastically) "Well, I hope your plane crashes".He would have been famous as a songwriter, but I wonder if he'd been as big a performer had Waylon Jennings been on that plane instead of Buddy Holly.
Bear in mind there was no personal animosity between them. They were just playfully bustin' chops as men in camaraderie situations of living everywhere together often do. Like the military. Or in a band.
Bros drive you bat guano. So everybody's sarcastic sometimes. But if you survived them, you have a hell of a story to tell.
And Waylon did. But in one of his last interviews I read, he also mentioned those parting words often kept him up many nights for the rest of his life. (As we can imagine.)