I would not recommend u to exchange your flat or real money for bitcoin. It's too risky. Better just sped some minutes of your free time with commenting and getting bitcoins for that. After u pass newbi rank u may join some campaign that will pay u 
Do you just said commenting is also one of the way to collect btc? How is that possible?
He is talking about signature campaigns posting here is also like commenting on a thread the term used is just different but with the same meaning.
It is very possible to collect btc with signature campaigns and many of us are getting it and find it really profitable and helpful.