I heard the $4000 Focal Utopia Headphones yesterday


Very nice. Very expensive. Beryllium drivers.  Reviews a bit hyped I think. Who would pay that premium otherwise? Not sure I could live just with any headphones still.

mapman
Beryllium dust is deadly but as no one will be subject to beryllium dust from a set of headphones I think you are good. I don't suggest that anyone should extract the beryllium diaphragm, drill it to create a cloud of dust and then inhale deeply :) other than that you are safe.
For far less yhe Stax Electrostatic head phones are magical 
There are many sub $1500 headphones that are exceptional. $4k for headphones is a rip off IMO.
Don't jump to any conclusion. If you have the means and are interested, give it an audition and decide if it's worth it to you. I did just that, after half an hour of listening to music of different genres, I bought it. And I already own the $3,000 Hifiman HE1000. Substantial step up.