It’s a simple rule of thumb that whenever the phrase “it is a known fact that” appears in such posts you can be sure that whatever follows is going to be 100% false.
This is no exception.
Examples of once domesticated animals that are thriving in the wild include:
Horses. Domesticated horses introduced to the US from Spain that are now feral.
Chickens. This is just one of the dozens of examples of escaped chickens that have gone feral in the Americas. Like the horses above, these were transported to the Americas as domesticated animals.
Dogs. Pets abandoned in the aftermath of the Chernobyl nuclear incident evacuation have bred for nearly 40 years.
More dogs. Also originally abandoned pet dogs (this time because of population housing policies), feral dogs have sufficient numbers in Romania to be classed as pests.
Rabbits. Domesticated rabbits originally introduced to Australia by European setters in 1788 now number in the millions. Feral rabbits are also a problem in New Zealand, as are…
Ferrets. Crossbred domestic ferrets/polecats introduced to NZ to combat the growing feral rabbit infestation have become a problem in their own right.
Camels. Also in Australia, domesticated camels released as a result of the growth of the motor industry are thriving.
Cats. Feral domestic cats in New Zealand have increased in population to more than a million, and have driven several native species to extinction.
Pigs. Escaped/released domestic pigs, originally introduced to the Americas by European settlers, have become feral across Canada and the northern USA, again with populations in the millions.
Cows. Populations of domestic cattle have been left to go wild on many remote islands, including the Aleutians in Alaska.
The actual fact is that almost every domesticated animal species, including those that were domesticated the earliest, is able to live in the wild. The most notable exception appears to be sheep, and even they have (semi-)feral flocks on islands near Scotland and New Zealand.
So @RichardG is wrong. The only possible point of interest (apart from learning about the species, size and location of feral animal populations) is which domesticated animals he might have been thinking about when he said “they are unable to live in the wild”. Hamsters? Canaries? Pekingese and Chihuahua dogs? Pampered Persian pusses? Goldfish? SIlkworms?
Answers on a postcard please.