why bitcoin is still illegal in many countries of world
Is there any solid reason behind this ??/
Illegal in many countries? It's a minority. Bitcoin is legal in most countries of the world. You need to go to some countries in the former USSR for bitcoin to be illegal.
Governments are cautious about it in the western world, but it's not illegal. The usual arguments are terrorist, crime, money laundering.
Before all the "get rich quick" guys came to the bitcoin space, it was a very political movement.
You need to go back in time to when bitcoin was first created.
June 2011:
I have become fascinated with Bitcoin since first reading about it a few weeks ago. It seems to me that a successful, thriving bitcoin currency is very threatening to governments, because it reduces their power to trace transactions, confiscate money, and pay their bills in inflated currency. Bitcoin takes power from government and puts it firmly back into the hands of the people. It has a small, but real, chance of becoming one of the most liberating inventions since the Internet itself, and will therefore be detested by governments around the world. If it is to survive, every effort must be taken to protect it from their attacks.
That was the general view. I'm skeptical if it does reduce a governments power: