Mercedes has 63 and 65 AMG models. (s63/s65, cl63/cl65, etc.)

Why do the 63 models exist ? What person is buying a car and decides to spend a huge pile of money on a car that is almost, but not quite, the top of the line model ?

Surely anyone that can afford a s63 could also afford a s65, so why get a louder car that vibrates more ?

What am I missing here ?

Why do the 63 models exist ? What person is buying a car and decides to spend a huge pile of money on a car that is almost, but not quite, the top of the line model ?

Surely anyone that can afford a s63 could also afford a s65, so why get a louder car that vibrates more ?

What am I missing here ?