The best investment is Bitcoin itself, or even other cryptos directly, but people always chase the wrong investments. 
That is just due to being greedy. I have seen many people are asking like "where to invest my bitcoins" or "how to multiply my bitcoins". In my opinion they are forgetting that their bitcoin itself a wonderful investment vehicle, instead of securing it, they ate looking for risking that gold laying goose. Greedy people always easily get trapped by scammers one day or other as they rush for multiplying their capital, their brain goes fade away.Fixed rate of return on investment is a scheme used to attract investors, that tends to fail at the long run, several factors do have an impact on the means of return on investment, I invest base on the product or service are project developers are out to deliver.
When no market is stable and not yielding in fixed rate then we cannot expect fixed returns for any investment. I guess only banks will be able to offer such fixed returns for our capital. But, world wide interest rate for fixed deposit is not good compared to what we do get from crypto investment opportunities.