We have dragged Reason from her Throne and set in her place the Empress of Dreams [liber Endvra]
Amor, sola lex
Each investigator loses 1 STA or 1 supply, it´s not losing 1 STA for each investigator....
Indeed, you're right, but I think Erik covered this when he said "a mixture of"
In any case, each investigator chooses independently from the others, hence, Investigator A decides of whether losing a Sta or a supply; after the choice is made and the effect applied, then it's Investigator B's turn to decide, and so on