Thanks to @colin for finding my old topic on my experience with spontaneous SketchUp crashes (link to that old topic below) with SketchUp Pro 2016 and 2017. Unfortunately the crashes I experienced were never understood or worked-around, so I had to stop using 2016 and 2017. As noted in my old topic, SketchUp would crash in my environment if I simply launched it with the default nearly-empty model, let go of the keyboard and mouse, and just waited. This was with an older macOS on an Intel iMac.