Not sure I can take this article very seriously.
But when they get to 2015 from 1985, a leap of thirty years, they arrive in a dystopia in which Marty’s nemesis, Biff Tannen, is rich and powerful. Tannen was able to parlay a purloined sports almanac from the future into a gambling fortune and casino empire.
Biff went back in time from 2015 to 1955, to give his younger self the almanac (leading to an error in the movie where Biff returns to the original 2015 timeline instead of an alternate timeline where he gave himself the almanac).
Marty and Doc then go back to 1985, where Biff has used the almanac sometime in the late 1950's to amass his fortune. It's in the alternate 1985 where he's built an empire.
My problem here is that even if an 18 year old Biff Tannen were able to come up with $10,000 in 1955, there's no way he would've been even remotely the mogul he became. He's got
twenty-eight floors to his casino.