I just wanna tell to my friend, that mostly of cloud mining are scamed their users. And i will suggest for make Investment on it, with can lost it. I can not tell him to stop because he has right for make a choice.

Nope, it's not good to stop them from investing on those ponzis, and you have no right to stop them coz it is their bitcoin, the only thing you can do is to warn him that ponzis has no good reputation and that most of the time it disappear along with his money without any traces...

You could show him some examples on the internet if he wants to listen to you, but if he has no plan to listen then be it, let him do his foolishness..  

At Least you can refer him to this forum and explain that not all services are that honest. Real mates should warn each other when they are about to be scammed. You can't warn him for all the bad things but that research he can do by his own

Let them know what you know about cloud mining but dont stop them because sometimes even though they know the risks involve in investing in those kind of sites they will continue to invest and try their luck in multiplying their coins through ponzis. Whats important is you shared your knowledge and give them a warning.

it is better to stop him by not investing on cloud mining site , if we get scammed by site should not happen to others ,best is educate him not to invest on scam sites and make him understand what is best investment strategy and where to invest    . it is guiding the person to right path.

For me, I'd give information or the dangers that occur when they do so. because if I am banned or give something bad to keep them away from it, I am going crazy because people nicknamed interfere with her activities. I'd advise him to do trading than cloud mining or fraud

If my friend invested into cloud mining, I will just tell him that the site he invested him is a scam. Most cloud mining return rates are absurd and can't be filled without it being a ponzi.

Of course I would suggest to him not to put any amount in any cloud mining companies even if they are legit.
Because once you send bitcoin to them it would be impossible for you to get your money back, so I tell him before he does.

That is the worst idea that a so called friend to advise you to do.
Cloudmining is a fantasy scam.

Obviously you cannot force them to stop as they are their own person but I would definitely warn them of the dangers and that they will likely get scammed, I would suggest rather than use cloud mining they try the altcoin market if they want to invest in something.