Take one female cat over a seven-year period. If all the kittens survived and bred, she would be responsible for 21,000 cats - they are such prolific breeders: you can see how important it is to neuter.
When I was young, I preferred dogs, but when I moved into a flat when I was 18, it wasn't practical to have a dog. So I got a couple of kittens, and that was it.
People's financial situation has changed, and they surrender their cats all the time, because they're downsizing or moving to a property where they are not allowed to have pets.