[SOLVED] Buying friend's i5 7600k GTX 1080 build vs keeping my 3600 GTX 1070 build?

Nov 1, 2019
I just bought the parts for a rig I want to build and the specs are:

Ryzen 5 3600
G. Skill Ripjaws V Series 16 GB (2 x 8) 288-pin ddr4 3600 ram (dual channel)
Seasonic Focus GX-750 80+ Gold Full Modular PSU
Asus Tuf Gaming x570 Plus (wi-fi) motherboard
Evga GTX 1070 8GB video card (bought used from Ebay, under warrant until December 2020)
Corsair 200R case
Samsung 860 EVO 1TB SSD
Windows 10 Pro OEM

Total build cost = $1245 (taxes + shipping included)

My specs for my friend's build that he is willing to sell to me for $900 are:

i5 7600K
Corsair Vengeance 16GB DDR4 2400
EVGA 850W Bronze Rated Modular PSU
MSI Pro Series Z270 SLI Motherboard
Corsair Air Flow 540 Carbon Black Case
Corsair H100i liquid cooler
Western Digital Black Gaming 500GB NVME M.2 SSD
Hitachi 1TB 7200rpm HDD
Windows 10 Pro
Logitech G602 wireless gaming mouse
IBuyPower gaming wired keyboard

My friend's build seems like a good deal and I am seriously considering buy his rig but I have some concerns. I don't like that his 7600K cpu only has 4 cores and I know it is fast enough to run most current games fine but I will run into trouble if games use more than 4 cores and it seems like games will start regularly using more than 4 cores in the next year or two. From what I understand, this 2400MHz ram is fine for Intel cpus but I know it won't be fast enough for a decent Ryzen cpu if I decide to upgrade in a few years to a Ryzen cpu. I also don't like that he only went with a Bronze rated PSU instead of a Gold but that probably is not a huge issue. It is tough, because if I bought my friend's rig and upgraded it in 3-4 years, I would have to spend $350-400 to upgrade the CPU and motherboard and possibly another $100 if I upgrade the ram. So, in 3-4 years, it would be a $500 upgrade. I don't know if the 1080 card will still be okay to play games on medium to high settings at that point? I do think that my friend's rig has a great case, I like the liquid cooling, the 1080 card, the M.2 storage and the included gaming keyboard and mouse.

With my Ryzen 3600 build that I current have the parts for, I could probably upgrade to a decent mid-range Ryzen 4000 series cpu for $200 and then buy a decent used Nvidia card for $200 for a total upgrade cost of $400. I know my PSU is top notch and I won't have to upgrade that.

I will also say that I am a pretty casual gamer and am just getting into PC gaming. I don't know exactly which games I will be playing but I will be playing many different types of games.

What would you do, buy my friend's rig for $900 or keep what I have that I paid $1,245 for?