As a power-user, I wonder if there is any reason to not do DIY PC building (for personal use) over buying from System76. It's not hard to figure out a good configuration online (or even just whatever System76 uses in their desktops?). Basic assembly itself isn't that hard (or time consuming), once you have all the parts.
And, I guess these days most people who would need a desktop at home with this configuration are potentially power users.
I have built a lot of desktops over the years. I've run into lots of strange issues. One machine would bsod like once a week and I never worked out why. Once a video card was somehow not compatible with the system despite being fine on paper.
It's just an issue of how you value time. I have no time for those sort of way issues these days. When a hard dusk fails I want to call a vendor and have them show up with a part, not screw around with some return to base arrangement.
I believe I count as a power user. Not wanting to humblebrag here but I have been using Linux since 1993, coding in Z80 assembly since 1987, x86 assembly since 1993 as well. As a university student, I have, in fact, made a little money on the side by assembling PCs in the 90s for others. Last I checked the CPU / cooler installation was way way too fragile for my liking. I might be outdated on this , I last tried like ten years ago and noped the hell out. I also do not have the need any more, between my laptop + eGPU for gaming and a rented Hetzner server, my computing needs are covered. https://www.hetzner.com/sb has a E3-1275v5 with 2x512GB NVMe SSDs and 64GB RAM for 46 EUR a month, it'd take quite a few months to make that server worth building and also I can use that thing to, you know, serve hobby sites.
I have done none of these things, but have assembled 3 computers now for myself and a family member.
There is nothing about CPU cooler installation that is fragile, I am not sure that you could, even if you wanted, put enough pressure onto the CPU to damage it using your CPU cooler.
The only really fragile thing are the pins on the CPU which you can damage if you mishandle it. Being careful with it there is really nothing scary about it.
It's very possible to damage the socket and motherboard, if perhaps not the CPU itself. Those heatsinks and coolers are heavy, and they do also rely on pressure for proper thermal interfacing with the CPU heat spreader.
And, I guess these days most people who would need a desktop at home with this configuration are potentially power users.