This idiom means basically means that you are safer doing something if there are a lot of people doing it rather than doing it by yourself (alone).
Sort of like a hive mentality. Your chances are better if there’s a lot of people around.
Do you remember the Twilight Zone Episode, “To Serve Man?”
So which one of us tastes better? Large, thin, dark, white, female, male, hairy, prepared with butter? Dipped in an egg batter and fried on a skillet?
Would you like a nice glass of Chianti with that?