[sh58]

fold equity is not important on the river, what you are talking about is how sucessful must my bluff be.

fold equity is the most relevant when there are cards to come, because you usually don't have the best hand, but by making a sizable raise you can make the play profitable, by winning the pot right there sometimes (fold equity) whilst also winning it sometimes by sucking out on later streets. obviously, this is semi bluffing.

the typical example of this is a flush draw on the flop. here you are a 2 - 1 dog, but by check raising allin you can represent enough strength to make an opponent fold (x)% of the time.

you can then add the numbers. say you can force them to fold 1/2 the time, the pot is 100, opponent bets 100, you raise all in for 400.
so you will win 200 50% of the time (100 in pot + opponents bet)

you will lose 400 33% of the time (your raise)

and you will win 500 16.5% of the time (the pot + plus opponent calling your raise)

so + 100 - 132 + 82.5 = 50.5

that check raise becomes profitable, you earn 50.5 on average every time you make the 400 raise, but it is only profitable because of fold equity