Considering 3 professional teams have left Oakland in the last decade, maybe the problem is with the city itself?
the city hasn't been perfect through all of this, but they were willing to give fisher what he wanted for the howard terminal ballpark and he bailed to vegas once he realized oakland was actually being serious. fisher/MLB were never serious about staying in oakland
the raiders left because davis couldn't afford a new stadium without public funding and vegas was willing to provide that while oakland wasn't. if i recall, the raiders wanted to redevelop the coliseum site but weren't able to because the A's had signed a new lease
warriors have always been a bay area team, not specifically oakland's team. they went back to SF because there was simply more money to be made playing there