I have heard and also read in various threads that mining is too risky. The invested money can all be gone with a blink of eye. Actually i am not sure wither i should do it or not. If i invest, then is there any chance to loss all the money?
If i invest, then what should be the amount first?
And in which sites would be better to do mining?
You are talking about cloud mining... In this case, yes, 99% of the cloud mining companies are scams. The rest sell you all their risk for a small part of the profits...
Actual mining is completely different: if you do all calculations and risk assesements beforehand, you're reasonably safe