This identity (with the minus) would be true if the only things you could do with Bitcoins were create them (at some cost) and then later destroy them for some kind of reward.
Since they can be transferred, it's analogous to saying that the amount of value produced by Visa is equal to negative one times Visa's revenue.
Don't you mean "All money that has even been invested into Bitcoin - total cost of mining = all money that investors will ever get back"
Cost of mining has left the system. "Investors" will never get it back.