Practical Poker Math

On average, over the course of 13 such bets you will lose 12
for a loss of $1,200 and win 1 worth $1,500, for a net profit
of $300 over 13 tries.
12 losses @ $100 ea = $1,200 loss
1 Win @ $1,500 = $1,500 profit
Net Profit = $300
With a profit of $300 over 13 tries, you can anticipate an
average profit of $300 / 13 = $23.08 per trial. The value or
expectation of each draw is +$23.08.
The sum of all expectations in any proposition must be zero.
You, as the player, have a positive expectation of +$23.08 per
draw and the person who laid the bet has a negative expectation
of -$23.08.
Fluctuation is short-term.
After 20 draws it would not be unusual for you, as the taker
of such a wager, to be down $2,000 and your opponent, who
made the proposition, up $2,000 — a fluctuation. While
after a small number of tries you might be down, it is almost
a 100% certainty that after 100,000 tries you will be up over
$2,000,000 and your opponent will be down over
$2,000,000 — an expectation.
Expectation is long-term.
The same applies to every bet or raise you make or take
playing poker. As long as all of your bets, calls and raises
carry greater money odds than risk odds, you will be a
long-term winner.
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Money Odds & Expectation