Another reason why this didn't connect with audiences
Obviously a big factor is that it was presented as a comedy when it's more of a drama, but I also think that there was a problem with the humor in terms of audience appeal, and that's that it was outdated.
I understand that an aspect of the movie is how Buddy's schtick is no longer current (the movie hits us over the head to make sure that we get it), and that wasn't a problem for me because I was more interested in the depiction of his rollercoaster career in show business. But I think most viewers would cringe at the variety-show scenes and Buddy's act because they were so old-timey.