You CAN drop a rank. so if for some reason the whole community decides to do this community goal right now, it's not inconceivable that if you do nothing at the same time, your rank will drop to E. As it says, it's a MINIMUM cash reward, not the cash reward that you will receive.
This is from my experience on Khasiri. I was rising and reached top 15%, then the next day I am back in top 40%. At the end I recovered and was in top 15% when the goal is reached.