Why would you invest in this type of mining ? You better buy equipment and hold it in your house or in a storage and you will be much more profitable and also much more safe for your investment
Best is to buy equipment and do mining yourself. But not every one has the capital to buy btc mining equipment and bear the electricity bills. If you have spare cash then why not invest in projects like OXBTC which can give you some passive income.
Because these projects are meant to exploit people.
First of all their mining farms usually don't exist and people buy false promises. Out of maybe around 50 cloud mining companies maybe 2 that I remember hashnest and genesis mining really had hardware. the other 48 were ponzi scams that disappeared long ago.
Cloud mining is too risky for an average investor and the money they can make every year is very small. Not worth giving away the control of your crypto to someone you don't fully trust.