Whilst Las Vegas is fairly safe for a big city, it is also a pickpocket’s paradise. What do people do when they go to Vegas? They get monumentally drunk and gamble. This means that there are thousands of people in a concentrated area carrying lots of cash, dressed in fancy clothes and jewellery, walking around unfamiliar places and- most importantly- not paying attention. It must be one of the easiest places to pickpocket someone or grab a purse whilst walking past without anyone noticing.
Don’t be the person that gets everything stolen as you were too drunk to notice its missing. Being in Vegas implies you want to go big (and probably not go home till the sun comes up) but you need to be sober enough to have your wits about you. Distribute your money about your person. Have a securely closed bag that sits across your body. Be aware of your surroundings- we all know that scene in every film where people crowd around a card table to watch- someone close by can easily snag something out of your pocket, don’t let them!