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.
You make it sound like there's a real change. But it's possible just like lottery is possible. Because changes to win that $2 bet 19 times would be 1 to 524,288. And change to win that 9 times is 1 to 512.
But your math is wrong, because outcome for that 9 flips with $500 isn't $1M but, just $256,000. You need 11 flips to get over a million dollars. and changes for that is 1:2048. So you can ask yourself, who would risk $500 for that because there's a change? And what game would even give you 2x odds with 50% change?