So my question is can bitcoin be a main currency of world economy?
The "don't like attitude" of most country steam from the rumors that bitcoin is being used for illegal activity like criminality (drugs, guns and even terrorist funding). However, there's always 2 sides of the discussions here. Yes there might be people behind trying to exploit one of bitcoins nature, but if you will have to take a closer look, its not anonymous as others think of it. If authorities really wanted to follow the trail, there's blockchain and blockchain analysis that can help them out uncovering those who exploited the system. But with the collaborative efforts of most countries, I don't think that we can see bitcoin treated as a main currency. Their will be lots of opposition, specially coming from financial institutions like Banks.
Bitcoin crypto currency transaction is now in the mainstream market, it is only the issues on Banned, Scammer, Hacking, and the issue on Regulation by government countries whom critical to the Bitcoin transaction in their market. Market is Volatile, anything can happen at any given time, market price value may goes up and down dependent on the Volume of investment in the market by the investors. the future is still hanging, but once this issue are resolved it will be good for the economy and the Bitcoin investors.