I'll go one step further: I used the LG 27" 5K Display for two whole years before returning to a 34" Ultrawide with a more typical DPI.
Obviously I preferred the pixel density and image quality of the high-DPI screen, but I find myself more productive on the 34" Ultrawide with a regular DPI. (FWIW, LG now has a newer pseudo-5K Ultrawide that strikes a balance between the two).
I look forward to the day that monitors of all sizes are available with high DPI, but I don't consider it a must-have upgrade just yet.
Also Note that Apple made font rendering worse starting in OS X 10.14 by disabling subpixel AA. Using a regular DPI monitor on Windows or Linux is a better experience than using the same monitor on OS X right now. If you're only comparing monitors based on OSX, you're not getting the full story.