Tom Arnold, who's currently at Sundance catching some flicks, told X17online that Jason Davis is selling his story about his family's failed intervention in order to buy heroin.

Arnold said Davis' "rep", a guy named Brian Quintana (who was involved in a sexual harassment suit against producer Jon Peters), is giving the "addict" money for his story, which Jason then goes out and uses to buy heroin.

"I just want [Jason] to live," Tom told us after admitting that Jason's siccing the police on him after the intervention was "embarrassing."

For the record, X17online didn't pay a dime for the exclusive pix and video of Davis, although the oil heir ended up in the hospital after suffering an overdose just days later.