Why did Al Davis move the Raiders from Oakland to Los Angeles in the first place? for what reasons?

I am completely aware of the fact that the Raiders are back in Oakland now, they started off in Oakland and thats where they originated, but the Raiders relocated to Los Angeles in the early 1980's and returned back to Oakland in the early 1990's, but anyway, what was the reason that Al Davis moved the Raiders to Los Angeles in the first place? Because I don't like the Raiders and I hate them more for being in L.A. for a bit, because pretty much L.A. is the Gang Capitol of the United States, everyone mostly knows that a lot of Raiders fans are mexican gang members, and thats probably the main reason why a lot of their fans are hispanic gang members, criminals because the Raiders used to be in L.A.