That's only if you loop the unbirhday quest (1000s of times). It's the only RQ that costs supplies/coins. You may not be able to gain millions of goods etc if you loop some of the other RQ's, like gather supplies/coins or spend fps, as many times as it's possible, but it's still highly profitable (in all eras), if you have a high level CF. 500% reward boost from lvl 80, for instance.
How many players want to sit around and loop 1000s of unbirthday quests anyway? Not my kind of role model, for sure