70k concurrent players peak on Steam, so at least that.
Steamspy also recorded a million copies sold. Just on Steam. So over that likely, too. Edit: For comparison reasons PoE 1 sold 700k within the first year. BG2 sold 1.5 million pieces in a similar timeframe.
You can't compare sales from twenty years ago and sales from today. Between 2014 and 2020 , there has been one billions more video game players in the world. I don't have the stats for 2000 but if the world gained one billions player in six years, imagine in twenty.
1.5 millions in 2000 is way more significant that 1 millions today. But still, that a great and well deserved success for Larian.