Not sure why you are posting here, as you are not new to the game and not an american manager. Perhaps to get some attention?
How is it possible that nation where the BB was created, never had a team winning a B3 cup?
Well there is no correlation at all between those two things so maybe that is part of it. In the past (and still a little bit today) It was not a good financial move to try to win B3 as there were always a few teams every year that buy monsters and just let their weekly debt slowly dwindle away their economy in hopes that they can with the whole thing, and then they fall off the map in the following seasons.
There have been 15 different countries that have had a manager(s) win B3.
There have been many other big countries with no B3 winners as well. Some of these bigger countries include:
USA, Lietuva, Hellas, Portugal, Pilipinas, Magyarorszag, Israel, France, Eesti, Brasil
Maybe there is a lack of talent among your managers, hmm..
I suppose it depends on how you clarify "talent". A lot of our managers in the top leagues help out with the NT and care more about other things than B3. I can easily throw it back at you and say how there may be a lack of talent in Serbia, considering your NTs (U21 and NT) have combined for 6 total trophies and only 1 Gold at Worlds, whereas the USA NTs have combined for 33 trophies and 5 Golds at Worlds. Maybe your nation needs to focus more on NT growth and training like the USA has. We just value different things I guess, and that is totally okay.
Once again, not sure why you have posted here, unless you just wanted to try to start a flamewar, but hopefully I kind of answered your borderline-rude question.
Murray/Harris/MPJ/Grant/Jokic - 2020 NBA Champs