While 150K is impressive in two hours and you are correct, that amount is certainly attainable it still took 28 player hours (14 players X 2 hours each) to get.
If a sweet base with an Item of Power and good defenses costs 20million then you are looking at 3,733 player hours to build your base.
If your SG does exactly what it did for 2 hours a day they will have to spend the next 133 days earning enough prestige to build their base.
And if rent is really 5% and rent on that base costs 1 million a week your SG will have to do exactly the same thing for 2hrs a day for a little under 7 days every week just to pay rent.
I am certainly on the bandwagon that it should take time to get bases and a super sweet base should be hard to keep, but at the same time these numbers seem a bit excessive.
I have no clue how a small SG with only 10 players could possibly have a base with an item of power. They couldn't build and maintain a base good enough to withstand any attacks, their IoP would be destroyed regularly.
