Why do I still feel like a failure despite career success and promotions?

When I was 17 I decided to make a career and get a high paying job.
And after Batchlors I achieved it very quickly.
My first job was as a software tester then a developer.
I quickly got promoted to senior developer within a year.
But I still felt like I was a failure.
I started looking around me , with career people have built relationships, talents, learn new things whereas I only wished for all of them
Due to embarrassment I never learnt anything new as I was just bad at everything.
Now I feel I am a failure, because now I want to get loved. And without any skills it's not possible.
Why do I still feel like a failure despite career success and promotions?
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