Actually; if you go all-in with AA and get called by an underpair you have about an 82% chance of beating him. But that's beside the point. Poker is not about winning hands, [/B] it's about winning money.
Supposing you're playing blackjack, and the house decides to make a rule whereby you are ALWAYS dealt an 18. If you play, you're playing at a "coin toss" of about 49%. But suppose the house tells you that winning hands pay 2 to 1! This is exactly what is happening in your poker analogy.
Let's carry this even further. Supposing you're playing poker in a 9 handed game; you pick up pocket rockets; and decide to go all in. What is the optimal number of opponents that you would like to have calling you? The answer is ALL EIGHT of them! You'll only win the hand about 30% of thlie time, but you'll be getting 8 to 1 on your money, and that's not even including the money in the blinds.