I never get tired of watching the sudden and complete change of attitude of bad guys when the good guys even the odds by pulling out their own guns in response to a threat.
They always go from arrogant to fearful. They drop right through "determined" without even stopping to consider an even contest.
It looks like the second guy was there as the comic relief. Watch him answer his cell phone right when the heist is "goin' down". What did he say? "Can I call ya' back, we're holding some dude up right now." If that wasn't enough, the display case jump-bounce was entertaining.
It was a shotgun that convinced them to try another way to get their spending money.