When my mother was still alive living in a council house she used to tell of a couple of families where the adult children sold their own homes, moved in with elderly parents and then a couple of years down the line inherited the tenancy, sub-let the house for a far higher rent and bought another house to live in, banking the rent each month. Everyone, including the Council, knew what was going on but nothing happpened.
Hopefully inheriting tenancies has been stopped although sub-letting at a profit still happens.