Keep in mind that the RE4 sales don't include neither of the PC versions (according to Steamspy, the PC Ultimate HD sold between 500 000 and 1 mln units on Steam) and the PS3/X360 version.
When we last had reliable Steam numbers for RE4, it had 915K owners according to SteamSpy:
https://www.resetera.com/threads/a-...les-on-steam-jan-2018-steamspy-figures.16153/