I'm building a Vegas Pro machine, which includes an MSI GeForce GTX 1070 Ti video card. I would like to get a 4K monitor. Do I need a G-Sync monitor for video editing? Or is it a strictly a gaming thing?
G-Sync only works on video games that render at variable frame rates, as it can prevent frame tearing when the frames being rendered can't evenly divide into 60hz (or whatever refresh rate you are using). The monitor is able to speed up or slow down its refresh rate in sync with how fast the game is able to render them. For video, it does nothing. If you want a monitor that gets the most out of Vegas, get a HDR capable monitor, especially OLED or QLED.
If you are trying to prequalify a new equipment expenditure .the place to do it would be on Tomshardware, where they have separate benchmarks for gaming and vide. Not sure if that applies to monitors, but its a good place to start.