Can someone help me out because I think I must be missing...

Can someone help me out because I think I must be missing something. The PFS shows 572,000 tonnes, or 1.15 billion pounds of copper, to be mined at a cost of about $2 a pound. We have a spot price at the moment of about $3 a pound, so that makes about $1.15 billion profit over 11 years (before royalties and taxes). That $1.15 billion figure is assuming a discount to the forecast copper price of $3.50 a pound, and ignoring the grade grade upgrade. So $1.15 billion looks like a worst case scenario.

What don't I understand?