A distant relative of mine (a teen) had a fixed-blade hunting knife of good quality - but in a cheap sheath. He sat down - the knife somehow got jammed against the seat, sliced through the sheath, and his main artery in his inner thigh. He bled out quickly.
I don’t usually carry a fixed blade, but when I do the sheath has rivets in it.
Accidents happen.
They are inevitable...but usually preventable.
I pride myself on knowing the orientation of my pistol and my folder on my person at all times.
One of the reasons that I do not carry a sheath knife is just as you stated.
I've had it happen.
I have nothing against sheath knifes, got quite a few of them, but there is nothing a sheath knife can do that a current manufactured folder of good quality cannot do, also.
My sheath knives usually reside in my go-bag.