Catalytic converters are targeted because of the precious metals that they are made with, namely rhodium, platinum and palladium. Thieves simply cut the catalytic converter from the exhaust pipe of a parked car and sell them on to scrap metal dealers. Taller vehicles are more vulnerable as the catalytic converters are easier to access.
To reduce the risk of having your catalytic converter stolen you could
For more information on catalytic converter theft, have a look at this BBC One Inside Out Catalytic Converter Theft video from March 2020.