Lets just say that you are serious about betting $100,000 on this fight with 5 to 1 odds.
Then why not bet $25,000 or $50,000 on the same odds. Why becasue if you loose you still have money left to loose some where else.
You loose everything and
You bet $25,000 you win you got $125,000
You bet $50,000 you win you got $250,000