It's far worse the other way around when you get it after buying it from Xur. At least you saved the coins. I bought Icebreaker, then I got it on the Nightfall a couple of days later. Same thing happened with Apotheosis Veil. I bought The Last Word AND grinded a shit-ton of glimmer to upgrade it. A couple of days later, I get it as a drop in Iron Banner. I only got 4 exotic drops in 250 hours of gameplay, 3 of them were stuff I just bought.