Back on topic, seems pretty clear that they have all been fairly unsuccessful.
Yes, and that's what I meant by saying that being a musician is tough. I'd hate to release an album, let alone a dozen of albums, only to receive mediocre attention. I hate when musicians struggle to make do with their music for a long time as much as old musicians who struggle to play but still do it.
Music is still a business and if your product doesn't sell a lot, that may simply mean it's not that good, to begin with. I know a lot of BS music is selling like crazy, but it sells because of good marketing and a dumb audience, so it's still a good "product".
If I were a session musician, I'd think 100 times before releasing a solo record because that means you lift yourself from being a musician to being an artist, and that's a completely different story.