What about next week?  Why put each week on a different address?

Consider this, the Ponzi grows and becomes a billion dollar a week industry.  Do you know what would happen, sure the OP is supper rich, but that's about the time some hacker breaks in and defaces the site.

The defacing won't be obvious, just an adjustment to the code that displays the address.  Perhaps they will simply steal the privet keys and disable the payment system.