Although major debate has been going on between whether Red Dead Redemption 2 or Call of Duty Black Ops 4 will end up being the top seller of 2018, currently we have seen Black Ops 4 snatch up that spot. In most markets physical sales are dying out while digital sales are not always easy to get the statistics for. Because of this, some have been drawing false conclusions from UK physical sales data which by all means is quite outdated, and perhaps irrelevant.
Since the NPD made data private and stopped announcing on their own, game companies now announce their own data, with Activision Blizzard stating that Black Ops 4 has made over $500 million USD in three days. This is still less than the record holding GTA V which is the best selling game of all time, and made $1 billion USD in its first three days, and even less than Black Ops 2 which made $500 million in 24 hours, but few games have come this close to matching those.