I think what happened is this: Julia got advertised as "Python syntax, C speed" but in practice it turns out to really be "Python syntax, 50% of C speed if you were willing to avoid some semi-well-documented gotchas, where avoiding said gotchas will take some non-trivial effort". Again, great if you are willing to work with it.
I am not saying that the Julia people are responsible for the "Python syntax, C speed" perception as much as that was what the prevalent perception became. And
I have talked to people in computational biology who tried Julia, and they said something or the other similar to "It just wasn't performant enough for me to give up Python," and if you really dig in, what really happened was when new people tried Julia with old mental models, they walked away thinking, "Heh, more MIT hypeware."