On paper the bet was free money. On paper. Expected value is the arithmetic mean of outcomes weighted by probability, and it is also a bedtime story adults tell themselves before doing something silly.
Where the lie lives
EV assumes you get to play forever. You do not get to play forever. You get to play until rent is due, and variance does not care about your spreadsheet.
The long run is a place most bankrolls never live to see.
EV = Σ p(x) · x — valid as n → ∞, and n is never ∞