"Hard Core Logo" plot question (unboxed spoilers)

Cafe Society
1

Hi folks,

first post as a paid subscriber (after being a lurker for about two years)

…but that’s neither here nor there…

so, my question:

Why did Bruce stab Billy in the back by asking Joe “How do you feel about Billy leaving Hard Core Logo” after witnessing the radio interview? After Billy reveals his new plans to the DJ and Billy rushes to the green room to make sure that Bruce is cool with it Bruce says “We’re cool, Billy boy. Just wait - we’ll show you how cool we are.”

I’m confused - what did Billy do to piss off Bruce enough that Bruce wants to break Billy’s secret to Joe?

Apologies in advance if this is an elementary-type question and I’m too dumb to have picked up the reason beforehand but I’ve watched the film a dozen times and haven’t figured it out.

C.

2

1.) Billy not telling his bandmates first, and to their faces.
2.) Breaking up what Bruce thinks is the greatest band.
3.) Doing it for the money.