Instead of inheriting the world-controlling mega-company ShinRa Electric when he was 21, after his father's death at the hands of Sephiroth, Rufus has been president since he was 16, when he successfully staged an extremely hostile takeover and his father died— though not at Rufus' hands, still by his orders.
One of Rufus' first acts as President was to have the department he perceived as his father's lap/attack-dogs— the Turks —terminated. With a bomb.
He then had to protect his tenuous hold on the Presidency by becoming a completely and totally ruthless bastard— not that he wasn't in the usual timeline, but take that and magnify it by a LOT. He grew up faster, under constant assault from outside parties looking to wrest control from a "simple" 16 year old, and he learned fast to be cutthroat and to offer no quarter. With only minor hiccups here and there, he's ruled the world since before he had to shave: his sense of entitlement is massive, his sense of humor almost nonexistent, and he's not going to even bother pretending to be nice.
If you don't know the games/compilation, this next part'll be a bunch of gibberish, but bear with me:
For the sake of simplicity, I'm saying Rufus used Deepground to eradicate AVALANCHE long before Barret and Tifa and everyone came along. He also had the Jenova Project terminated early on in his presidency, probably via several bombs. This means Cloud Strife and Zack Fair were killed in captivity, and Hojo was killed with great relish. Cloud Strife therefore never gave Sephiroth the black materia, Sephiroth was left rotting in the northern crater, meteor was never summoned, the lifestream never rose to save the planet, and ShinRa never fell. The world climate is, however, very tedious, and despite the lifestream never rising, Jenova has other ways to activate the illness Geostigma and infect the world.
Rufus is only just showing the beginning stages of Geostigma. He'll be a little weak, and very, very, very leery of being touched. He can, however, see out of his left eye again, since he was never in the explosion that originally damaged his vision.