No one's blameless, and therapists are trained to dissuade you from blaming yourself. They're biased in your favor or at least have to give the impression that they are, even if you're a thoroughly wretched person. Obviously, no shrink is ever going to tell you "Yeah, you're pretty much scum for even thinking that. If you don't feel terrible about yourself already, it's time to start..." It never happens. So, no, you can't trust a therapist who tells you you shouldn't blame yourself, because that's what they have to say, no matter what. Nor should you blame yourself, regardless.

There are other people you hold in low esteem, right? If you have low-self-esteem, you could be one of those people, and your analysis could be spot-on. Most people who enjoy the fruits of western industrialized civilization do not really deserve the level of material comfort we enjoy relative to the great unwashed.
The thing is, it does no good to blame yourself. It only makes things worse. It makes you into a bitter, toxic person who brings down other people and causes additional harm. All you can do is forgive yourself and move ahead from where you are.

Also, your perception of yourself is to be trusted less than what others think of you, if for no other reason than majority rule. If you think you are thing A and everyone else who knows you tells you (really, literally tells you out loud) you are thing B, you are probably thing B and you are probably wrong about yourself. (And even if you're not, you might as well be.)

And no, I'm not a therapist either, I'm a crazy person who is going to the doctor tomorrow to get help. But not in the form of counseling. Talk therapy for psychotic depression is rather like taking a strong bridge hand to a machete fight...