Master nodes surely will be dominated by entrepreneurs and big investors but we still can have good profit being early investors. Who knows may be later some renting tokens type things will be introduced to become part of nodes by renting your tokens. I didn't read deeply about nodes but saw this model in other projects in past.
Yeah, They could do something like what Waves does. SONM team could develop leasing feature, Where small investor will lease to form a Node and receive payouts accordingly.