Most efficient way of earning bitcoins today is offering services and getting paid with it.
Simple, legal and efficient.
What you are saying is true but it will never generate 1 btc in a month and it will give you only limited income so if you want to earn 1 btc in a month then you have to take a risk of investing higher capital either in trading or in any ICO as if price pumps then you will be earning good profits regularly but higher capital is mandatory to get higher profits.