I would not prefer "diagnosing", but because I have the same issues, I can reply what are the underlying issues. I mean, why would writing the truth kills? What people write in their suggestions is most of the times inacurate, anyway. Speaking the truth may even produce good results with motivating someone to pursue the long term therapy.

So,

That's because you feel worthless deep inside yourself. And you feel worthless because of some other reasons before that. But because somewhere long ago, you already knew this is a terrible way to feel, you had 2 options to choose from: first is, not feeling so by thinking others are worth less, OR, thinking I'm worth less then others so you wouldn't have to feel worthless because you already know you are worth less then others. Well, same as me, you choosed the first tactic. Which tactic you choose basicly depends on what you lean from how people communicate at home - but it doesn't matther - even if they are bashing others and that is the reason why you learn it, don't blame them because of the tactic you chosen - you could have chosen the second one, and it will be the same. Neither works in the long run, anyway.

The reasons for this are basicly the same. You want to feel superior to hold on to your fake image.

You must know, though, this image of fakness can be dissarmed by feeling what should be felt (the original pain you felt before you chosed tactics).