Why other players don't matter, with math
JJCoolL830, it still doesn't matter. While hitting will reduce the running count on average, it doesn't change the true count on average.
How about a contrived but useful example...
Let's assume you saw the dealer's hole card, and you know the dealer has a hard 16. Better yet, you are Rainman, and you happen to know that there are exactly five cards left in the deck and you know exactly what they are...
Of the five undealt cards in the deck, four of them are tens, and one is a five.
You confidently stand on your hand of 12, knowing that you will win this hand 80% of the time.
Now all you have to worry about is Joe Sixpack at third base, taking away one of those dealer bust cards. Should you care? Of course not. Here's why.
Let's assume he draws a card.
4/5 of the time, he is indeed going to hurt your chances by drawing one of those four ten-valued cards. When that happens, he reduces your chance of winning this hand to only 75% (three out of four cards are now tens).
However, 1/5 of the time, he is going to draw the dealer's only hope, the last five in the deck. When that happens, you're a 100% lock to win your hand.
So, what does his hitting do to your chances on average?
(4/5) * 75% + (1/5) * 100% = 80%.
So, if he stands, you're an 80% favorite to win the hand. If he hits, you're exactly the same 80% favorite to win the hand. This is not a coincidence. It works with any number of cards and players. Other players CANNOT affect your chances at all.
Extra info for the technically inclined:
With 5 cards left, the running count is +3, and the true count is +31.2. After he draws a card, there are two possibilities:
4/5 of the time, running count = +2, true count = +26
1/5 of the time, running count = +4, true count = +52
So, after he draws, the average running count is reduced to +2.4, but the average true count remains unchanged at +31.2.