But if I bet a guy off a dry pot and loose to the all in player, who cares because I’m loosing that pot anyway and it doesn’t matter to me who I loose to.
The whole point of bluffing is to win the hand, when your opponent(s) fold. Sometimes the third player will call, and then you lose your bet, if he has a better hand. So in this case you took a risk with no reward. Lets take an actual example to illustrate the point. The board is 9h8h2c, and you have 7s6s, so you flopped an OESD. The all-in player has As2s for bottom pair, and the third player has KdQc for two overcards. The equities in this 3-way pot are as follow:
7s6s - 46%
KdQs - 19%
As2s - 35%
In a normal hand, where all players have significant chips behind, 7s6s could bet here and most likely make both opponents fold. Its pretty tough to continue with bottom pair no draw in a 3-way pot, especially if you are not closing the action. And KQ cant really continue either with just overcards and no draw. So in this case the semi-bluff will likely work, and the
equity of 7s6s will go from 46% to 100%, which is a significant gain. However when the player with As2s is all-in, they can not fold. And for that reason when KdQs fold out, the equities will change to:
7s6s - 50%
KdQs - 0%
As2s - 50%
So in this situation rather than increasing your equity from 46% to 100%, you only increased it to 50%. The all-in player is happy however, because his equity went from 35% to 50%, so your bet mainly protected him from getting outdrawn by KdQs, which had 6 outs to a higher pair.
If it’s early in a tournament then it doesn’t matter if the short stack goes out.
That is true, and it also does not matter much at a later stage, unless its on the final table or right on the bubble. If its 80 players left, and 71 places pay, the EV gain from seeing someone bust is very small. The far more important consideration is to not bust yourself, if you have a decent stack. If you succeed in that, someone else will take care of busting 9 random players, so that you get in the money.