If you have working prototypes and a community to collaborate them, getting funds for actual testing it in silicon is not that hard esp. not if you collaborate with an University. With good performing silicon one can then expand and the folks who designed it are garanteed to have a job updating and enhancing it for the next 10 years or more :) Esp. if other companies sponser their work.

Are the Mills creators afraid say Intel will use their ideas and create their own chips excluding them from business?

ARM itself is beaten by RISC-V's initial Rocket prototypes in power and area and the upcomming BOOMs are a good match for ARM Cortex A15+ (only 64 bit). And they only recently started just with OoO chips. And do you see ARM suddenly creating RISC-V chips? or borrowing their ideas?