Set the SIM PIN before the phone gets snatched

A snatched phone that's locked down costs you the phone. Unlocked, it cost one reported victim his entire bank account — around 50,000,000 VND (~$2,000). Motorbike thieves grabbing phones out of hands at the curb is an old Vietnam risk (the UK FCDO calls motorcycle bag-snatching common — surrender, don't struggle); the modern damage is digital, because an unlocked phone lets a thief drain banking apps and e-wallets and take over Grab before you've flagged down help.