If there are 1000 shares per machine, and 750 shares are sold to the public. Doesn't that mean there's a 250 share or 25% per month service fee?
Not at all. 20% is being kept by the mining op and re-invested into additional hardware at no additional cost to the share holders.
As far as a fee goes if group buy 2 is successful it will be 2.5% as there will be total of 2000 shares issued and only 50 are being considered as management fee shares.