Moving to DC is to have meetings all day long with political party members, wine and dine with government lobbyists off the record, back scratching, back room deals off the record likely the most important aspect, etc...

When you're a member of the Inner Party the bellyfeel is doubleplusgood.

Echoes of Boeing moving its HQ from Seattle to Chicago to DC area.

It makes more sense for a defense contractor like Boeing to have a substantial office (if not their HQ) in DC given the Pentagon and all the program offices in the area. Especially since lobbying is the only way they can get business, not by the quality of their work. For non defense/intelligence contractors it makes much less sense to be in that area other than a small office at most.

Boeing is primarily a defense company - DC makes sense.

It mirrors the absolutist monarchy of Louis 14, where courtiers needed to be available for his lavish feasts (and couldn't be elsewhere to plot on their own)