You get exposed to a lot as a young person these days, more often than not before you are 16, and not in far flung exotic places either. Local parties, parks, school etc. its all going on there.
the violence you've read about really is extremely isolated, just look at the regulars shock at when it had happened. dont believe the hype. i live in dundee, and if i go out in town, in pretty much guaranteed to see it kick off at some point in the night, pretty much same as anywhere in the UK. if you compare that to three weeks in total i've spent in ibiza, going out practically every night and haven't seen once single fight or anything like aggresive behaviour (with the exception of some rude folk in Space).
going to a nightclub like pacha means they will be less likely to be drunk due to the price of alcohol, and im sure you'd know if you felt you could trust them with regards to other things. if you aren't sure you can then thats fair enough but its a shame. personally if i was in ibiza as a 16 year old and couldn't go to a nightclub id be gutted.