I did not know that. Then it means that they were already on my balance... I was rather confused, when I saw "You Have Won" message and balance did not change. Thanks for that notice.
Sharing my experience: I've been collecting free BFG boxes since they appeared. Not a frequent collector, but got already 1462 BFG

Cant stop doing it; it is already like a habit to me. Cant set a goal, when I will start gambling with BFG and dividends

Were you able to collect 1462 BFG just by the free boxes? I claimed it a bit in the beginning when it came out but stopped doing it when the rewards dropped pretty big. Personally, I would never gamble with my BFG tokens; I only play with my dividends.