Yes, she should have been more careful, but you call the person who had their cash stolen the stupid person?..
The real stupid person in this whole story is the thief that stole the money. No thief, no problem. She simply returns to the restaurant and gets her purse. End of story.
The thief just saw the opportunity. Who is the stupid person: the one who grabs an opportunity as it passes by or the one who unwittingly GIVES the opportunity to the other person?
"No thief, no problem"?? No stupid amounts of cash lying about, no problem. She wouldn't even go to the restaurant to get her purse because she didn't leave it lying about. End of story.
I had to pay in cash for a couple of transactions during my "adventures" to get to and to stay in the UK. It's straight from the bank to the cashier's office. Maybe a stop at both ends to hide the money about my person. Heck, I don't even count the money at the bank in front of the other "patrons," it's been a modus operandi of some gangs to have a person in the bank "marking" victims for their accomplices to rob at an opportune time and place.
When I was in university and travelling from home to school, my parents would give me pocket money "just in case." Just a few hundred pesos in case trouble arises and I need some cash. I would only have maybe a Php100 on me for food and fare, the rest I would make sure to hide carefully.