I entered the Pokerstars Guinness World Record NL Hold'em tournament. It had 225,000 entrants. I made it to the final 11,000 players. Made it to the top 4%.
I was running good, I didn't get too lucky and my big pairs weren't cracked. Then I made a mistake with pocket Tens, calling an all in and then folding to a bigger pair. That caused me to lost half my stack. So I waited, got Aces under the gun and went all in with my remaining 11,000 chips. Of course, some Russian donkey with 110,000 calls with King Jack and makes a straight. It was as good a chance to double up as you can get: one opponent, 80% favorite, and forced out all other speculative hands.
Never be upset if you get your money in that good and lose.