I am not exactly xaurumQA but i can answer your question and i believe xaurumQA will confirm.
Revenues on the sheet-paper that company provided are very approximate and was made for easier understanding since you must understand that revenue and price of XGM depends on many variables. But i believe that even with so many variables in play mr. Gaper Kenda made calculations well below of what is expected. So numbers could and i believe it will be even better 
But yea there are many things to take in the account:
- speed of burning XGM
- value of buildings when they are build ( could be well above 10 mil. and we bought gamma at 5,48 mil.
)
- speed of xaurum coverage and price of xaurums
- price speculation on exchage ( i won't sell my gammas neither at 500 $)
- ......
I agree with you, except on last point.
I'm not selling mine below 1000$

You are correct.