It makes a ton of sense to me (Gen X). In this — and every other paragraph after “So I quit.” — it sounds like you feel guilty on behalf of all millennials. Other people’s situations are theirs. You don’t need to apologize for yours.
As you said a few paragraphs up, you worked your ass off, doing unfulfilling work. Wouldn’t some call that “paying your dues”? The loads of work experience that you got earned you some entitlement. Earned entitlement is different than assumed entitlement. It’s the latter that millennials are stereotyped with.
When you posted that tweet, you knew — at least subconsciously — that you were ready to change your situation. It was a sign that it was time to shake things up or leave. Sure, one should generally refrain from criticizing their employer on social media, but it happened and placed you on a new path.
You got what you needed at The Post. It was time to move on to the next experience.