If there are 10x engineers, it's a right place, right time situation. Very good engineers with the right experience, luck, a good idea, and the relentless desire to execute. Miss any of those things, and you can still be a a multiplier, just probably not 10x.
Even so at my companies the difference between between good engineers and bad is massive (a lot of the difference is talent and motivation). Imagine you had a company full of shitty engineers, a motivated good engineer in the right could deliver 10x the value of some shit engineer
There's honestly quite a few developers that produce zero or negative value (e.g. by implementing the wrong things, introducing lots of bugs or significant complexity etc). 10x:ing them is not difficult.
Even so at my companies the difference between between good engineers and bad is massive (a lot of the difference is talent and motivation). Imagine you had a company full of shitty engineers, a motivated good engineer in the right could deliver 10x the value of some shit engineer