I'm the author of the post. Yeah you got it right, I think the hiring process got me into that mindset, i.e. "This is a step back from you title-wise but you'll get back there quickly". So the hiring process made all that look too easy and in retrospect got me into the wrong state of mind.

What I should have done, at the point of being hired, is to drop all that, and focus patiently on what I needed to do. And I'm sharing it because not enough people share this side of it, and because I am working on elements that would have made it better. Thanks for reading! :)

It sounds like a very painful experience. Thank you for writing about it and sharing what you have learned.

I definitely thought like the first commenter at first but the realization that you admitted what you did wrong and accepted responsibility for it really won my over by the end of your post.