because you never know

[james0228]

[ “Your phone is being spied on so I tell people not to bring their phones when they’re coming to the protest,” he said. “I tell them not to even dine nearby the protest. Sometimes we don’t give out our real names to people we meet at the protest because you never know.”] about chinese protest from the korea herald .

what is the meaning of the underlined clause ?

 

[grassy]

You never know who they might be, e.g. spies sent by the government.