Free bitcoin mining scams in world

As you see presently due to value of bitcoin there are so many bitcoin scam websites comes and offering good return in less time.
But as per my view without work nobody can give free money .
It means these websites gives money for small amounts initially and when customer attract and invest huge amount with believe on website
Then just see they will close their withdraw or website.

So I appeal to all before invest such websites think twice times and work only initial time
Otherwise you will loose the money.