I spent 325 locust swarm on one of the item stage which is around 2.76 B. At the end of the EB I had 419 successful action. I made 2 B for the whole EB and got 15 feathers. So basically I lost 760 mil gold on this EB. If you want to make gold on this EB, better skip the Locust swarm item phase and hope someone generous will do this item phase. Sorry Dev, failed EB. Better go back and re-do a better payout.
If you don't like it don't do the event it's simple, I always chuckle at all the cryers in forums when an event happens.