Aldon Smith's alcohol problem got so bad, he was drinking every single day ... and people close to the embattled NFL star are concerned he'll drink himself to death if he continues down this road.
"I'm worried for him. I'm worried for his safety," one source close to Smith tells TMZ Sports.
"He's an alcoholic. It's not about football anymore. We're hoping this is rock bottom for him."
We broke the story ... Aldon checked into a rehab facility on Sunday after a domestic violence incident with his fiancee .