What causes diamond bits to slip when drilling into extremely hard formations?

Many think that the reason is diamond powder can not open sharpness, the head of drill bit is too hard. Someone will try every methods to reduce the hardness of the head and wear resistance.
This leads to the other extreme situation, where the drill bit can drill into extremely hard formations but has an extremely low bit life.

In fact, when drilling extremely hard strata, the rock wears the diamond too fast, but the rock wears the diamond head relatively slow.In this way, in the very short time that the bit is drilling, the rock wears away the diamond and a small plane appears on the diamond surface.These facets greatly increase the contact area between diamond and rock, thus reducing the unit area between rock and diamond contact pressure on.
When the pressure applied to the rock surface is less than the compressive strength of extremely hard strata, diamond can not effectively break the rock, when the drill bit can not drilling into the rock ,  slip phenomenon appear.