Big tournaments

The best decision I could have when playing big tournaments is patience... playing calmly without pressure... I have managed to go further like this... than trying to steal jackpots or get into very weak hands.

Patience is the superpower of big MTTs. In deep stack tournaments like WCOOP, SCOOP, or large fields on GGPoker/PokerStars, the one who survives the most is the guy who waits for the +EV spots without forcing. Those "jackpot steals" or heroic calls on weak hands are the fast track to the rail — and to eternal tilt.
You are 100% right: playing calmly, without pressure, you double up 80-85% of hands pre-flop and explode in the spots where amateurs vomit.