Value is about the price, not certainty: an outcome with fair odds of +100 still loses about half the time, and a bet with a 30% chance loses most of the time even when the odds are generous.

The question to ask isn't "did it win?" but "was it placed at a good price?". Keep stakes consistent and small enough that a run of losses doesn't damage your bankroll.

Read more: Variance and Long-Term Results