[rznicolet]

Everything coming in speeds up when it falls to earth.

Tiny stuff burns up completely in the upper atmosphere, where the pressure is low, because they have low surface area per mass -- the atmosphere can stop them entirely. Their terminal velocity is low. (That is, when the velocity through air is high enough that the drag prevents gravity from speeding up the object any further.)

Medium objects have a higher terminal velocity get deeper into the atmosphere before exploding. Fragments from these (which now have higher surface area per mass) can then be slowed further by the atmosphere and make it to the surface, but not so dramatically. Bits of the Chelyabinsk impactor fall into this category.

Big objects have a high terminal velocity. They make it to the ground largely intact... and without being slowed as much by the atmosphere. That gives you craters and bad days for being a dinosaur.