@gdenisse,

You gave points that I so got interested in

First, feeling that I can do it and no one tells me NO.
Another cause is Social Acceptance, because others do it and I want to fit in and be accepted.
Some do it as an escape route from their fears, anxieties, depressions or situations they are experiencing that they believe they cannot face in any other way.

These are really true. When people feel no one can talk to them or advise them, they fall victims of such issues. Some want to do it because of inferiority complex.

JESUS CHRIST is truly the helper of such people.

Best wishes!