Even if you start with $2 and go all in every bet @ 2.00 odds, after 19 bets you will be at $1,000,000. Or if you start with $500, it takes 9 all in bets to reach $1,000,000. It is possible.
It's possible to arrive at that amount; that's it. You make those series of bets in a role going all in without losing, which is also on the second thought not possible; if it were that easy, most casinos would have been out of business for a long period of time now. I can't say it's entirely impossible to get such a reward, as strange winnings do happen, but such is hard to fine and very uncommon.