Is stealing catalytic converters a thing?

[Esceptico]

According to my neighbour the catalytic converter from her (quite old) Prius was stolen yesterday early evening from outside of her house.

Anyone else come across this type of crime? Seems and odd thing to steal to me.

As an aside the thief must be mighty brave or mighty stupid because we live in a square with houses and flats all around so can't understand how they managed it without being seen.