Soft 18 is one of those hands that is not always played to its best advantage. Most blackjack players see that their hand total is 18 and stand, thinking that they have a pretty strong hand.
And in some cases standing is still the most advantageous blackjack strategy play to make. If the dealer’s upcard is a 2 through 8 it is better to stand.
If your blackjack strategy includes assuming the worst case scenario is that the dealer’s hole card is a 10, then he could have a 12, 13, 14, 15, 16, 17 or 18. Since the dealer has to up on the 12 through 16, he stands a pretty good chance of busting. If he has a 17 you will beat him with your 18. And if he has an 18 you will push, but at least you will not have lost any money.
It is only when the dealer’s upcard is a 9, 10 or Ace that your blackjack strategy changes.
Normally if you were playing with a hard 18 you would be stuck and would have to stand. Assuming that the dealer’s hole card is a 10, he would then have a 19, 20 or blackjack. This would cause the hard 18 to lose, but having a soft 18 gives your hand a second chance.
While there is nothing you can do to beat a dealer having blackjack, you do have a shot at beating his assumed 19 or 20. Here, your strategy would be to reduce your Ace from 11 to 1 so that you are now playing with a hard 8. Now you can hit and possibly build a hand to compete with the dealer’s assumed 19 or 20.
You might beat him or you might not. But at least playing your soft 18 this way against a dealer 9 or 10 you have a chance, whereas a hard 18 would leave you standing with no chance to rebuild your hand