While legislators may be elected based on a political agenda communicated in campaigns, those bullet-point agendas have to be translated into legislative details. Somebody has to write the laws. Legislators are, after all, lawmakers. While there is no mandate that legislators be lawyers, a JD degree is excellent training. Legal expertise is very beneficial for a legislator to carry out the technical parts of the job, including drafting and editing proposed legislation.
Financial success in real estate relies heavily on an agent's sales skill. That is how real estate agents get paid: selling real estate. But each transaction involves a contract with two or more parties agreeing to specific terms. Real estate agents guide their clients through the terms of transactions. Expertise in law, and real estate and contract law, in particular, can be a great background in the real estate business.
Few professions require people to read and write as much as the legal profession. While legal writing, especially contracts, requires specificity of meaning --- the opposite of fiction or poetry that may seek richness of meaning --- lawyers are very well trained in the mechanics of writing.
Many lawyers design their careers based on an area or areas of law they are most interested in. If an attorney has a specific interest outside of law, he can pursue his interest by choosing an organization --- a business or nonprofit --- involved in the endeavor. For example, a lawyer interested in the music business might seek position with a record company, rather than being an intellectual property specialist at a large law firm.
As with every other kind of writing, the enormous volume of legal writing done by lawyers has to be edited by someone with expertise in law. But legal editors aren't limited to editing the mechanics of legal writing. The bulk of legal editors' task is verifying facts in legal writing.