I would say a combination of already being rich, being old, and insider trading. Congress can't actually take personal funds from lobbyists legally.
Maybe if someone is in Congress, they can skirt the law around lobbyist gifts due to your position of power, but 1. it doesn't sound very plausible that someone becomes a multimillionaire by squirreling away illegal gifts or campaign funds and 2. to become I doubt small town city councils making these decisions are in a similar place. Most of reality is boring and not like the movies.
Still very few for deserving a tax break based on potential employment opportunities. A DC simply doesn't help the local economy, it's very often a net-negative: it's very resource-intensive while not generating much in terms of economical activity for where it sits at.
In a sense it's purely extractivist consuming land, water, and energy without benefits to the community.