you explain it very odd but you are right for the most part. all except the very beginning.
if he is playing on 1080p and upgrades to high end vega the 2500k will 100% bottleneck the gpu. i would guess even a 2600k would bottleneck if he went high enough.
also a new cpu is not a waste of money if you are on the 2500k. a new cpu/motherboard/ram would give many new features, speed, reliability, cooler, and energy efficiency.
Interesting replies from both 'Salty Mac' & 'NandorHUN'.
For the record, I'm gaming on a 1440p/144Hz monitor. Right now, the only game that I've actually struggled to run is PUBG (which is still in Early Access anyway).
Concerning the news (or lack of) today of Vega's two-month wait. Well, it's a bit disappointing that AMD is still lagging behind NVIDIA when it comes to the higher end cards. VOLTA could well trump VEGA straight off the bat ... :(
hey you got your 1080 price drop, you getting one??