All good answers. Be especially careful when walking along side a busy road - don't have stuff slung over your shoulder if you want to keep it. Better to face on coming traffic (though people sometimes ride on the wrong side of the road). In such a snatch you might get injured - but its rare for foreigners to be directly threatened with violence, knives, guns etc. Injuries are usually consequential. Incidentally, Vietnamese are victims of this kind of snatch crime too if they are also careless. Many of them carry surprising amounts of cash.

In my experience, the risks are having an over-ambitious schedule which makes you tired (especially if you're prone to jetlag) - and then getting sick, trying endless exotic food just to be cool - and again getting sick, hiring motorbikes when you have no idea about the traffic in Vietnam - especially after booze etc.

For blokes its also about getting ripped off in dodgy bars - mobile phones/wallets etc being lifted, or bills you can't understand etc.