It decreases the edge because you are not making the optimal bet all of the time. You don't always win when you have the advantage, and can lose big bets while winning small ones, and that is where the swings in the game come from. After 100,000 hands using your method you could be up 800 units while you avoided the swings. Using optimal betting you could be up 1,200 units, but be suffering from angina like you had too many rides on the Statosphere roller-coaster.....if you are playing at all at that point.

