I know why they made it free to pay now. I was doing the calculations.
P = players
I = Items (Like hats, weapons, etc.)
$ = monies
I$ = Items purchased
if I = $ then
if > P then more I$
> I$ = > $ for VALVE
In Lamens terms, the more people buying hats and stuff, the more monies for VALVe.
???
Profit!