Just last year it took a trio of TitanX GPUs to eek out under 30 FPS in games. The 1080 is nice but 4K gaming from what I'm reading is not possible at 30+ FPS with a single 1080 GPU and high settings in modern games.

I worry you'll dump thousands and learn this first hand.

For now, try a nice 1080p display laptop which the 1080 will drive at top speed in games.