Doesn’t have to be that much if there are enough of us. Exeter have been fan-owned for years. Wimbledon are fan-owned and have just built a brand new stadium in London!
Incidentally, fan-owned doesn’t mean that wealthy individuals can’t invest, they just don’t get to have a majority stake. For example, in Germany clubs have to have at least 50% of the shares owned by its members, rather than investors. So we could go down that route and Mr Swann or any other person who loves the club and wanted to invest could do so but they wouldn’t be able to own it or take decisions without the approval of a majority of the members. Seems like the best of both worlds, no?