I believe that usually market makers will not make money by creating markets with initial funding and a reasonable fee (<2%). A regular bet will usually be a fraction of the initial funding since bigger amounts would shift the price significantly. However -they provide a public good since as long as a automated market maker is active it will incentivize people to report on the likelihood (by buying and selling shares).
So maybe "crowdfunding" will be a way to finance such market makers. There are a lot of topics with big public interest. Another option would be to even only allow those who participated in the crowdfunding to trade the market. In this case it is more a competition against the other participants in contrast to funding a public good.