IME, carbide studs do get rounded if you ride bare ground.
So, if you ride hard, and/or is VERY attuned to the response of your bike, it's probably possible to notice a degradation in performance.
I suppose it's possible to call that "worn out".
Most of my miles are commuter miles. And while I might push the riding envelope wrt weather and mileage, hard cornering isn't one of my trademarks.
And while I certainly have managed to round mine off, I've never been able to reduce the height of them to any noticeable amount.
It's usually the base of the studs going through the casing and rubbing holes in the tube that's my limiting factor.
Some studs have carbide cores and steel mantles, other have carbide cores and aluminium mantles.
Those with aluminum mantles have a slightly better "self-sharpening" ability. The mantle wear away faster, leaving more of the narrower carbide tip exposed.
Exactly how much this helps WRT traction, I can't tell.
Visually, it's quite noticeable.
And certainly looks like it could do some good.