There are some sites for investing bitcoins but sooner or later they becomes scam.

Scams are certainly common, but I wouldn't go as far as to say that they are all scams.

that's called Ponzi's ! Tongue

don't go with these it has high risk I am sure if you invest there you will always lose your money in these types of sites

That's funny coming from somebody with "HYIP" in their name!