For people who (like me) are restricted to buy economy.
If you are a CFP, buying a P-class premium economy ticket allows you to travel in Magnifica for free (provided there's an I-class seat available).
You spend 12500 miles for the upgrade, you earn (let's use MXP-JFK as an example) 4009x2 miles (for the P-fare), + 4009 (elite bonus) = 12027.
It's a 1600-something ticket, as opposed to 2400.
Not too bad!