5820K is still a perfectly capable gaming chip, especially at 1440p and 4k. Whilst others were buying 6600k and 6700k or the 4690k and 4790k, some of us purchased the 5820K for more future proofing if you may say. The only downside is we have to wait a fair bit longer before we can see some significant gains. However someone using a 4 core non HT like the 4690k or 6600k would see a good gains by upgrading to a 3600 or 3700x. The same could not be said for us. Most games are using 6 cores right now, it will take a few years before we see the majority of the games using 8/10 cores.
Solidly put, my friend. Really does explain it all. Yeah, I bought the 5820K as an upgrade from the famed i7 920 (D0). What a chip that was! But clearly there's still more years in this CPU I have now, so I will stick with it for a while longer.