There is absolutely no need to start insulting me, Pete.

If you believe that there are tungsten carbide tipped drill bits that CUT into masonry just like a twist drill bit cuts into wood, then can you explain why a masonry drill bit doesn't have a sharp edge on it like a twist drill bit does?

That is, how would this drill bit:

http://blumol.net/images/products/b_rtryhamr-db.jpg

be optimally designed to CUT into masonry when there are not sharp edges to it? Don't you agree that the only edge that can be argued to be "sharp" might be the one facing directly forward, in which case it's not designed to CUT masonary as it rotates.

On the other hand, it's easy to explain why the shape of that tip is designed to bash the masonry in front of it into dust.