Does anyone know how many people is using bitcoin very often and how many are "weekends" users, with weekend users I meant people who bought it and hold it for a long time
You can only estimate, its around 3 milions i heard but its difficult to predict.
Thing that can be said for sure is that around 31 million transactions have taken place in bitcoins history. More than 25 million addresses have been referenced in those 31 million transactions. The total number of addresses, gives an upper limit for the number of possible bitcoin users.
But not every address ever referenced is still in use. And it turns out that less than 10 percent actually have any bitcoins in -
fewer than 2.5 million.
So that is your final number of bitcoin users - 2.5 mln.