He had released the genuinely successful "Sally can't dance" (his earlier records were critically acclaimed and "cult" but not really successful even if "Transformer" was big in england due to the glam-rock/bowie-connection) where he worked with Steve Katz of Blood, Sweat& tears, complete with "crack" session-musicians and big horn arrangements and shit.

His next studio-album however was the double instrumental noise LP "Metal Machine Music" which at the time was considered one of the most unlistenable albums ever made (I think it's pretty cool but I like noise) and then spent the rest of the 70's doing what the fuck he wanted. While I guess some later albums like "New York" became fairly successful, they were just blips on the radar in the grand scheme of his discography. Basically, I think he prefered to be an underdog/cult-artist rather than a big star...