Much smaller area (DC is something like 65 square miles) and population, for one.

But beyond that, my thought is that although you probably have fewer super rich people in DC, you also have way fewer poor people. So the average is going to be higher than even SV.

Plus, the types of jobs in DC proper (so we’re not talking about the extended Maryland and Virginia suburbs) are almost entirely professional/government. It’s also a very expensive place to live.

DC has higher GDP per capita than California for the same reason NYC would have higher GDP per capita than NY state, or San Francisco than all of California. Cities are more economically productive than areas that also have lots of low value added activities like agriculture, mining or forestry.