Rubbish. The button offers a risk free death. Whereas even bullets to the head can potentially ricochet from the skull or lead to nothing more than brain-damage.
There are a myriad of ways to guarantee death in relatively painless ways...some are reputed to be even enjoyable to some degree.
The fear lies in the process rather than the outcome and in this regard pressing a button is no different to squeezing a trigger or pushing a syringe.......