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Because for now it is the only one that has all that features combined:

  • 4k resolution
  • 144Hz frequency, for showing up to 144 images per second
  • Nvidia G-Sync, for rpeventing tearing

    Tearing example
  • HDR, for increased contrast

In case it is too expensive, I recommend looking for a monitor with the same features but lower frequency. The difference betweeen 144Hz and 120Hz should be almost indistinguishable.