This certainly doesn't require 100m, just some time. Regardless, this seems like a neat place for feedback.
Does editorial consulting for small business have any legs? Most successful people can write well enough to not embarrass themselves, but what writing I see could still use a lot of work and has awful style. So I would charge hours for revising any important non-legal documents--letters to investors, for example, or, as I've been doing a bit of, business proposals and introductory documents for start-ups.
The general response I get from most people is that they don't need it. I suppose this comes from a broad tolerance of mediocre writing among most small businesses. But I also believe that good writing can make a difference of some kind. Older men I know complain that their new hires cannot write a sentence, and that ineffective writing hurts the firm's image or wastes the time of people who have to revise that work. I've imagined that, should I be able to acquire some clients, I could also come in to teach a few short classes to a sector of the business that aim to break bad habits and offer quick tricks for improvement.
So, not a million dollar idea, but something I've considered putting a lot of time towards this summer. How obvious is it that I'm an English teacher who would like to earn more?