Big assumption there. It's Mohsen ffs - as if he is going to service it himself.
My best friend has an E39 actually. He has spent thousands getting a few things fixed (ABS computer, fan transistor, dead coilpacks, other stuff I cannot recall atm). More stuff to break = more expensive to maintain. Me and my mates with jap cars (all older than his bmw) have had no such issues of similar magnitude.
I agree with regards to oil/filter type stuff, but most are too pussy to get their hands dirty these days and there is also that bullshit 'it's a BMW' mentality which means many owners are too scared to do anything themselves, and 'specialist' mechanics end up charging through the nose. Have seen it first hand several times.