https://www.cougarboard.com/board/message.html?id=34500058
1) If I'm unfamiliar with an airport I'll be navigating I always arrive 2.5 hours early. Every airport has it's own weird peccadillos/busy days/unpredictable bureaucracy—from rental car drop offs to special oversized luggage drop off locations.
2) 1 out of every 5 trips I have to deal with extra security snafus that can't be predicted, bags pulled for batteries or camera gear, and that usually adds 15-30 minutes to moving through security.
3) More than a few times someone in my group has forgotten a passport/drivers license and needs to rush back to retrieve it (I hate it, but it's nice to build in a mistake buffer for the same type of person who complains about getting to the gate early).
4) Getting to the gate earlier gives you a chance to sweet talk the agent to get an upgrade.
5) Arriving at the gate with enough time to hit the bathroom so I don't have to use the bathroom on the plane is always a win.
6) Sleeping in for an extra hour just so you can be stressed out through the entire airport process and arrive at the gate just as its boarding isn't pleasant in any way, shape or form.
7) I can promise you, it's more annoying traveling with a lazy person than it is with someone that gets you to the gate early.