Not only do you have to be lucky in achieving the right outcome, but you also have to avoid the wrong ones on the way. It implies a certain level of complexity or layers of contingency in order to come out ahead. In Craps, Hard 6 & Hard 8 are the longest odds (9 to 1) that hinge upon more than one throw of the dice (avoiding 7 or other combinations of 6 or 8, respectively).
Commander Adama's raid on a Cylon base in Battlestar Galactica. Firing a missle and hoping it destroys the base in one fell swoop is like betting on snake eyes (1+1). The odds are long (30 to 1) and hinge on one result. But coming up with a strategy that involves the use of decoys, anticipating enemy responses, etc., requires everything to go as planned but it gives you better (some would say more realistic) but still long odds (9 to 1). That's why "sometimes you gotta roll the hard six."