I would think discount tire would be happy to sell you the warranty; usually warranties are where businesses make huge profits. Some of them have large markups, but even if not a lot of people never bother to claim even if they could. Personally reminds me of having to deal with an insurance claim, I'd rather just buy a new whatever then have to prove or do paperwork to redeem a warranty. Now if you know the company such as Discount Tire has an no hassle claim process that could make more sense.
But I still don't understand why people are excited to buy this Discount warranty. In my discount shopping cart its around $50 per tire? So basically instead of a warranty on 4 tires I could just buy a 5th tire. I have had some tires fail in my 26 years of driving, but certainly not one out of four. Now if the fee is the same for much more expensive tires that could make some sense. Maybe I'm missing something? Or maybe some people just enjoy the peace of mind of "insurance" on their tires?