How long have you been in therapy, may I ask? If you're still fairly near the beginning then it makes sense that you just don't "get" what your therapist is trying to say to you.
Your posts show that you don't think you are worth esteem at all, and this is because your self esteem, self worth, self belief are rock bottom.
Learning that you are worthwhile, that your thoughts and opinions carry weight and can be important to others as well as yourself, that you matter to others and to yourself (currently you don't seem to think you do), this all takes time.
You have no good opinions of yourself, because you have had them knocked out of you.
Your first step is to understand that you have as much right to self esteem as the next person.
Your next step is to find something that you consider is good about you - there will be something, even if it's something like "I have good hair" - it's a start. From there, you can find other good things about you, things that you like.
Then maybe you can think about things that other people may have said about you that are good, but that you have tossed away as being untrue, because you don't feel you deserve them. Think again about these things - are there any common features? Can you even remember any positive comments people have made about you?
Self esteem is not a myth and YABU and obstructive to think so BUT that is because of where you are at the moment. Therapy can take a while to get to a breakthrough point (2 years is a common breakthrough point) and until then many many people fight against what they're discovering in their sessions.
Think about it like this - you are facing a brick wall. You know this brick wall, you've lived with it for a long time. It stops you getting anywhere but that's good because you're scared of what is on the other side of it. Therapy will help you to deconstruct that brick wall - but it's scary! You don't know if you're going to like what's behind it! So you might take out a brick at the edge. Then maybe another. The therapist might push you to take out a supporting brick near the middle, but that's too much - too scary, too soon, no thanks. Another edge brick might give you a glimpse of what's beyond - but again it might be too much, so you decide to go to another edge instead. Anything to avoid facing the unknown in case it's worse than what you know!
Slowly slowly you start to come to terms with the removal of bricks, and the eventual disintegration of the wall - and then once you hit the core support bricks, the wall comes tumbling down quite fast. But that takes time (and, as I've said, 2 years is a common period) because you have to make yourself accept what you're doing.
I wish you luck in your therapy - and believe that you will come to accept that you are worth as much as the next person - give it the time it needs to bring down those bricks. 