What prevents gravitational collapse in string theory?

Understand

It is conventionally believed that if a ball of matter of mass $M$ has a radius close to $2GM$ then it must collapse to a black hole.

• But string theory microstates (fuzzballs) have no horizon or singularity, and they do {\it not} collapse.
• We consider two simple examples from classical gravity to illustrate how this violation of our intuition happens.
• In each case the `matter' arises from an extra compact dimension, but the topology of this extra dimension is not trivial.