I don't understand, if shoud exist the Datacenters, it looks so.
Why they scam?

they can earn many BTC this this datacenters.

do you believe really hashscam has a real datacenters ?
that wasn't true

HashNest? I think they are ''legit''. That site isn't profitable. Same kind of Genesis Mining and another 'legit'' cloud mining sites, where you buy some mining power and never make ROI.
HashOcean was very profitable, very good to be true.
Yes all the cloud mining site that have promising profits will collapse eventually, but if we are smart in investing there will not be a loss.