Start with something smaller or find an interested wealthy patron. Same options as if I wanted to start a business that will take years of development to achieve traction.
How does anyone get a following? You build it over time.
I can assure you there are a lot of great books that would not have been written if the authors first had to either 1. become beloved enough on the internet that they could crowdfund their income for five years or 2. somehow secure a "wealthy patron" who wanted to finance it (I can imagine a pretty fierce competition for that pretty rare beast).
How does anyone get a following? You build it over time.