Bill Maher has not changed his tune about the problems with young people ... he says one of the root problems is the musical messages pumped into their brains.

The 'Real Time' host made his case that the music industry has been singularly obsessed with the almighty dollar and the things it can buy. BM says back in the day ... there were only a handful of songs about the pursuit of cash.

These days, Bill says, the charts are flooded with the pursuit of all the goodies money can buy. Even in a country where "Rolex on a Redneck" is a big hit!

He says there's a sociological element when it comes to rap. The Black community was denied access to wealth and opportunity for so long, when it finally started seeing some inclusion, rappers flaunted their success.

But, as Bill says, the money obsession in music is everywhere ... and growing. E.g., Bruno Mars' "I Wanna Be a Billionaire So F***ing Bad."

And Bill says these musical messages get burned into the brains of teens ... like the first time you saw your father coming out of the shower!

BTW ... you should watch 'Real Time.' Bill's one-on-one guest was Killer Mike, and he was amazing!