Economists cannot predict the future, as much as some people might wish they could.
Whatever break even point the devs of Anno 1800 considered when making the decision between releasing only on Epic and releasing to all platforms may have seemed reasonable at the time the devs were gearing up to release the game, but performance of said game is never guaranteed. Sure you may have statistics to influence things one way or another, but it's still a gamble.
We don't know if Epic exclusive + late discounts > full game purchases on all platforms specifically for Anno 1800, and it appears that you're claiming which way that equation points with no evidence. Do you work for Epic? For Ubisoft? For Blue Byte? Are there public sources pointing to game sales? What research are you pulling from that considers game futures?
I will respect that you're right about predicting devs' decisions based on which way that equation points. Everyone is downvoting you though because you're making it seem like you know the answer when clearly there's more to this game, and financial gaming decisions like this.
You're not an expert. You're a chatter. Unless you can prove otherwise.