With internet almost run over by all kinds of scam artists, spammers, pedos etc. is there any surprise that such a thing can happen? You have crackers trying their level best to install keyloggers and other tools to read the passwords to your accounts. And in this environment if you hand over the key of your apartment to some complete stranger, I think the writer should also take some blame for his naivety. Just beca…
The internet is not "almost run over [with] scam artists, spammers, pedos etc." They are visible and use anonymity to do what they do on the internet, certainly, but it is far from overrun.
Secondly, is it really too risky to be asleep without a locked door between you and the world? That is a scary, closed world to live in. You are also wrong to blame the victim; they say themselves they made a mistake not to do more verification, but the blame can only be on the perpetrator †.
Finally, let's not forget that most sexual assaults and rapes [1] are carried out by friends and acquaintances, so limiting your contact to friends of friends is unlikely to make you significantly safer.
Overall, I think your conclusions are the worst to draw from this attack. Take care, but don't go crazy keeping out the "other".
† It might be useful to make a distinction between casual responsibility and moral responsibility. The victim may have done something that helped cause the attack, but they are not at fault.
[1] According to (admitted a random googling) the American Centre for Victims of Crime, 77% of rapes are committed by non-strangers. http://www.ncvc.org/ncvc/main.aspx?dbName=DocumentViewer&...