Canelo Alvarez and Gennady Golovkin are gonna fight ... 'cause there's too much damn cash at stake not to ... so says one of the best MMA fighters of all time.
TMZ Sports talked to Tito Ortiz in L.A. Thursday night ... and asked the UFC legend whether the fight every boxing fan wants to see ... Alvarez vs. GGG ... will ever go down.
FYI -- people in the boxing world have accused Canelo of ducking Golovkin.
Tito's adamant the fighters WILL square off ... and explains why money -- not fear -- is why the men haven't thrown down.
Check out the clip!