Getting on the FP is not necessarily a condition for a sale.
As it had been said before, it is good for you exposure.
And now, the most important question: who sees your items? Who visits your shop while you are on the FP? Probably me, or other sellers, in search of clues about how you got on the FP .... At least that's what I have been doing when visiting the shops featured on the FP.
Given the huuuge types of products that are being sold on Etsy (and of buyers in search for a specific product), the short period of time you are on the FP and the fact that you have only ONE product exposed, what is THE PROBABILITY of a match between your product and the needs of a potential customer ? Ok, there might be a match, but perhaps not in what regards your prices/color of the item/shipping time, etc
Ok, you might say that a buyer in search for a pair of earrings that resembles your featured item could visit your store in search for a pair of earrings that he needs ... I agree ... so the probability mentioned earlier will slightly increase. But still ...
This is how I see things ...
PS. hope you all understood what I was trying to explain here, English is not my native language :)