[Swordmaker]

5k display? You cannot use a toolbar in many programs with 4k. You cannot make bigger.
I use 1920 x 1080 screen resolution so I can easily see the buttons.
I suspect people who use 4k and now 5k create those hard to read websites with tiny fonts.

Another one from the Peanut Crowd (PC) ignorantly chimes in. I use a 27 nice 5K iMac at work. What you complain about is not a problem with a Mac. . . Unless you use a Windows virtual machine in it. Windows has problems with such high resolution screens and adapting windows and webpages to high-definition screens. Macs do not.

[minnesota_bound]

https://www.howtogeek.com/206710/should-you-buy-a-4k-computer-monitor/

FTA: Mac OS X deals with this better, as the scaling features that enable Retina displays on Apple’s Macs also work for 4K displays. Some applications still aren’t updated to work with this properly, but most Mac applications now support proper display scaling. Apple has also updated all the included Mac applications to look good on a high-resolution display, while Microsoft hasn’t done the same for some included Windows applications — though with Windows 10 things are much better.