Conor McGregor just went off in his UFC 229 press conference -- vowing to destroy Khabib Nurmagomedov ... and claiming he'll be a billionaire by age 35!
Conor showed up alomost 30 minutes late to the event in Las Vegas -- blaming crazy traffic. Khabib had left by the time McGregor showed up.
But Conor didn't disappoint ... screaming about how much he hates Khabib, how great his whiskey tastes and how much money he expects to make.
Dana White had told us McGregor could make a Mayweather check ($100 mil) but Conor says the number will probably be closer to $50 mil.