do not buy cloud mining unless brand is reputable (ie has proven to ship, own and run mining hardware)
This is only part of the equation as their are many other reasons to avoid cloud mining:
1) Increases centralization which is bad for the bitcoin ecosystem vs buying asic hardware yourself
2) Rates often are unprofitable - Use a decent calculator
https://bitcoinwisdom.com/bitcoin/calculator and enter in an expected average difficulty 5-20% to see if ROI
Please check here as a
starting point for research into credibility of cloud mining.
https://bitcointalksearch.org/topic/m.9697654Companies that aren't labeled as ponzis can still be scams as well , but this is the minimum bar one must look at as a starting point.
1) how does it increase centralization ? Last time i checked (will vary on exact service model provided, but still) cloudmining doesnt attribute new mining, rather transfer ownership of existing hashrates. Depending on exact terms of service, theoretically users can aid DEcentralization by selecting alternative pools
2) yes. and no. far too many, far too volatile factors will shape the final return. Whilst obviously everyone wants to make money, the ROI is near impossible to accurately predict. I'd say cloudmining shouldnt be seen as a sure-fire way to make money,rather it should be seen as a way to try out mining without taking on the risk of spending > $2k on mining hardware then have to have all the associated headaches (cooling, storage, noise, maintenance delays etc). You can switch on / switch off your cloudmining at any point, and see daily BTC returns (even if miserly) and at worst, youre risking 10-15 bucks to learn first hand. On the other hand if you make a paltry 5mBtc per day for a year and Bitcoin raises by 30-40% you could see a significant ROI.
basically its low-entry, low-risk mining - users can try it, hate / love it, continue / dump it without ending up with the world's most expensive heater in the garage
i agree its a complex process, but i cant see how it hinders the BTC ecosystem or how anyone can say with confidence what their ROI will be