I liked how the black bum ended up with the gold, but the way it was executed was lame (the guy just telling Bill Paxton to take off after the explosion, and then Paxton just gullibly does so even though the gold is sitting there right next to the bum).
It needed something more than that.
http://www.manlymovie.net/
You're an IDIOT, Paxton's character was just counting his blessings that he made it out and wanted out from the start
sharePaxton's character was less sharp than Sadler's character was (e.g. He thought the gangsters would have let them go if they traded Lucky). Paxton's character also wanted to alert the police and, thereby, give up the gold; so he wasn't greedy.
Hence, it made sense that he would run away at the end. He wouldn't have the brains to see that Bradley was lying, and he likely wouldn't have cared, as he doesn't want to die for money.