Why are Metamorphic Rocks more resistant to weathering and erosion than Sedimentary Rock?

The rock is more dense.

Explanation:

If you look at the rock cycle, you'll see when sedimentary rock goes under extreme heat and pressure, it becomes metamorphic rock. So the metamorhpic rock is so much more dense that the rock is like a sedimentary times ten! I mention it's more dense because they're is more rock to erode away. Making it much harder to wear away the metamorphic rock.