Feeding dry food only to your cat, especially your male cat, is dangerous. Feeding it ad lib is particularly harmful.
Dry food is convenient and the premium diets are well-balanced with all nutrients - except water. The cat's urine becomes super-concentrated, predisposing male cats to blockage of the urethra.
If the male cat is also overweight and not very active the risk of blockage increases.
Cats on an ad lib dry food diet tend to become overweight. Dry food is like space food. A lot of calories are packed into a very small package. A tablespoon of dry food is equal to a can of wet food. Cats grazing on dry food all day and not moving around much are bound to pack on the kilos.
All cats have a poor drive to drink. In the wild most of their fluids come from their food. They avoid water sources as that is where they are most vulnerable to predators. A cat on a dry food only diet drinks more than a cat on a wet diet, but not enough to remain properly hydrated.This puts pressure on the kidneys. When they are young they can compensate to a degree but as they age it may accelerate kidney failure.