It's hard, but not impossible. As a curious point, I heard about people that pay to others to play rift battles for them. I mean, I've never reach that score before, but I think it's possible.
Screenshot at 14:27, july 4
Screenshot at 23:10, july 4
Screenshot at 12:28, july 6
Screenshot at 16:42, july 7
Screenshot at 13:04, july 12
Screenshot at 22:52, july 14
Screenshot at 03:16, july 16
Screenshot taken feb. 11 2019 20:27 EST
Screenshot taken feb. 13 2019 10:42 EST
Screenshot taken feb. 14 2019 04:38 EST
Screenshot taken feb. 14 2019 22:15 EST
Screenshot taken feb. 15 2019 00:22 EST (suspicious).
Screenshot taken feb. 15 2019 02:41 EST