Back To The Future: 1955 Marty Improved Biff's Life - Theory Explained

https://screenrant.com/back-future-marty-biff-1955-life-change-improve/

While Biff is seen getting George's car nice and shiny and it's portrayed like he's now beneath George, there's also a truck in the background that says "Biff's Auto Detailing." That means that instead of working a job he hates and is unqualified for, Biff now owns and operates his own auto detailing business. That's a huge improvement by any metric, going from 9 to 5 employee to one's own boss. The theory also suggests this change came about as a result of Marty McFly causing Biff to wreck his car and get it covered in manure. Getting the car thoroughly cleaned would've cost a good amount of money, so SatNav believes that instead, Biff did the work himself and along the way discovered he had an aptitude for it.

Thus, Marty's interference ultimately improved Biff's future. The theory is plausible enough and could be slotted into the canon fairly easily, if not for the fact Biff seems genuinely afraid of George, and is also kind of tense in his interactions with the McFlys in Back to the Future's fixed 1985. That suggests the old Biff might still be bubbling under the surface waiting to get out, and resentful of no longer being the dominant party. This is further supported by old Biff readily stealing Doc's DeLorean time machine in 2015 and using it to make himself rich, pointing to his not being truly happy in his work in auto detailing.