Guaranteed Blackjack Winner?

When browsing one day I noticed something that said I could be a guaranteed winner online, so I downloaded it. I like to read these things and see how ridiculous the theories are. This proposed a theory of playing blackjack and everytime you lose consecutively, you would just bet the amount of your consecutive losses so that when you finally win, you cover your previous losses. Then you go back to your normal amount and stay at it until you lose again, and then follow the same system. This got me thinking about the system, and I have been thinking about it for days now, and can't find a huge flaw in it, but I am sure there is something I am missing.

I realize that you could lose a ton of money if you hit a very bad streak,

(-5,-10,-15,-30,-60,-120,-240,-480, -960
On a table with a $1000 limit, you would have to lose 9 straight times for this system to fail!)

but with that being very unlikely to happen, I don't see what the problem with this system is, please help.

Also, the theory says same system can be used for roulette too, by just betting the same color everytime.