PTSD can come from any trauma, big or small, depends on the INDIVIDUAL, and NO ONE else.

Teaching someone positive coping skills to recover from PTSD is key. (not laughing at them, ridiculing them, abusing them).

EVERYONE suffers from trauma. EVERYONE. Getting over trauma takes time, just like grieving over any kind of loss.
Stages: denial, anger, bargaining, depression, and acceptance, in that order. Help others by allowing them to grieve at their own pace.