is it possible that the forecast of its decline in bitcoin prices is caused by the new REGULATION enforced by governments that prohibit crypto?
no.
the drop would have happened like this one way or another. the negative news that you keep hearing has been around all through past 9 years. none of them are new. they may have grown in number in 2017 but as you can see price was rising in 2017 despite all the same news being around.