Plenty of stadia exist on valuable land. Besides, there are environmental issues due to the tank farm near the stadium leaking underground (which may or may not have been remediated). As long as Qualcomm Stadium isn’t touched, they can be largely ignored.
I’m sure Citi Field in NYC plus the tennis stadium stand on more expensive land, notwithstanding proximity to LGA airport.
Let’s hope the Chargers go fuck off to Hell Ay, and any plans to redevelop Qualcomm are stalled for a while.