8800GTX maintained it's premium price point the entire time until something better came along and it's a LOT more difficult to maintain a $5-600 price point than a $170 which the 6850 didn't even do.
That entire time wasn't that long. I am too lazy to look up camelegg prices for 8800GTX but I am pretty sure it lost $150-200 over time as well.
5870 could be sold for $300 even after something better was out. It doesn't matter if it was because of bitcoining.
Again, you are missing the point that before 5870s became hot again, they were going for firesale prices for $180-225 for months. Also, the 6950 provided cheaper and faster performance than the 5870 way before the 2 year mark from 5870's launch. Right now, the 6850 still hasn't been surpassed by any 28nm next gen card for $169, 2 years later. Another point you keep missing: 8800GTX $600 was bested by a $200 next gen card barely 2 years after. Sure, if a person timed the 5870's sale perfectly, then it can be said it held its value well, but in general all 6850s held their value well, not just in the used market but on Newegg. The same can't be said of 5870s, which dropped like a rock on Newegg way before the 2 year mark, and 6950 made that card irrelevant. What card makes the 6850 irrelevant right now on Newegg for $130? Nothing, 2 years later still unbeaten.
In fact, GTX480 was going for $175-225 on Newegg 2 years after the $369 5870 debuted. That undermines your point even more. I can't go out now and buy anything that's 40-50% cheaper than the 6850 and faster at the same time. And that's exactly what GTX480 did just 2 years after the 5870's launch.
Yup, sold my 5870 at the peak of the bitcoin craze for $300. Not bad to only lose $70 in 14 months on a high end card. I then went ahead and paid $50 to upgrade to a 6970, lol! In contrast, the poor saps who bought a 7970 at launch for $550 would be extremely lucky to get $400 used after only 8-9 months after release.
You can't look at it like that. The person who got a 7970 at release has paid for all of it through bitcoin mining if he took 10 min to set it up. People who were willing to take on more risk, paid for 2-3 7970s. Many enthusiast $550 adopters of the 7970 knew this perk existed and took full advantage of it when the mining difficulty was still low. :thumbsup: