This is in contrast to the rest of the movie building him up as someone who can be annoying, but is good at heart, and deserving of sympathy. In his own words, "I'm the real article. What you see is what you get." And also, "I am many things, but I'm not a thief," when cons are ironically a form of theft.
I'm sure some fans will attempt to defend this with victim blaming, even when some of these victims were children, or that the pair needed that $100. This overlooks how Del shows no remorse doing it, as it looks like something he regularly does, and how the two still had their credit cards at this point. Hell, Neal Page could have pawned his watch alone for more than that.
Otherwise, a great movie.