"You see this book?"
"You see this book?"
Just as I surmised.
Biff would start making wager after wager, eventually winning a lot of dough.
It wouldn't take long for someone to find out just HOW biff knows these things, and they'd forbid him from betting.
Like someone who makes a killing in the casinos.
You'd quickly be "invited" to never return.
One of my favorite time travel movies is Time After Time, with HG Wells coming from 1890 to 1979.
He finds out that girlfriend is going to be murdered in the upcoming week by Jack the Ripper and goes to her apartment with a gun to protect her.
The cops nab him and question him.
He explains over and over to the police who he is, and how he came to the future.
Finally he says: OK, I'll confess to ANYTHING! Just send a car!
The police do and find a dead body in the apartment.
In the movie, the cops just say "I'm so sorry, you can go now"
In real life, no WAY they would just "let him go".
They'd beat him with a rubber hose until he spilled his guts on just what ELSE he knows.