Miners are buying the cards at almost any price.
I don't think we can take that as evidence that all or even most gamers are happy with current prices.
Let's also not blame Brexit for this... both the 1080 and 1070 were released *before* the referendum, and showed that nV had priced all their Pascal cards a tier higher than Maxwell.
And finally you can eliminate the Brexit effect altogether by comparing the price in USD. 480 released as $239. Before the 390 release the 290 price had settled at $249, down from initial release of $399. The 390, despite being a re-brand, was bumped up to $329 on release.
The point is, even if you compare in USD, we've had the same perf for $249 since... let's see... Q4 2014. That's when the 290 was widely available at this price. Now the 480 is the same perf, give or take, for the same USD, 3 years later. USD prices have not been affected by Brexit
Some people say, "You can only compare release prices!!!!1 LOL", but the point is you could get 480 perf for 480 price in Q4 2014.
Brexit still had an effect and the 1080/1070 prices were affected as most retailer pay on account in USD (30 days or so), so they had to pay for them after Brexit. This means on some cards they lost money, then the price went up.
Without Brexit and mining you would probably get an 8GB 580 for £170 or less. 8Gb 480s were available for a short period under £180 early this year with the Brexit effect, so would have been even cheaper with out it.