As others have pointed out, lots of people relocate to the LA area and they tend to keep their loyalties after they settle in rather than adopting the Rams. With nearly 4 million people in LA it doesn't take a huge percentage of 'enemy' fans to make their presence known.
I wonder how many Charger fans have relocated to Kansas City (population around 500,000)? If 3% of the LA population are Bills fans that's 120,000 people. If 3% of KC's population are Chargers fans that's 15,000 people.
And I'd bet a ton of money that way more people have moved from Buffalo to LA than have moved from all of California to KC.
AlbaNY_Ram