No they don't. I have met a large amount of people. Even the nihilists believe in some sort of meaning. Furthermore, it is literally impossible to function without a believe in something meaningful, which can not be backed up by evidence given we have no facts to evidence that any action, animal, thing, matters at all or has any meaning.

Just waking up the morning and brushing your teeth is the acknowledgment that your teeth are meaningful and that your health is meaningful. Even if you are purely hedonistic you acknowledge that your pain and pleasure is meaningful.

If you are a functioning human you believe that there is meaning, and that is a belief that can not be backed up by any sort of conclusive evidence.