The Fame (Monster) sales doubled the Marilyn Manson album, and the other two albums MORE than doubled the Manson albums.
Gaga was much bigger and it doesn't resemble Manson's. If anything it resembles Britney's when the sales are translated to 2010s standards - gradual decline but still very very popular.
The kii is when they say "people don't care" yet they obviously care enough to open up multiple threads about the state of her career - which is clearly far more stable than theirs - daily.