Cloud mining was profitable back 6 or 7 years ago but now I don't think so,
Back then everything was profitable, buying hash, selling hash, everyone made a profit.
It has nothing to do with any one method.
Buying hash from a rental service is biased toward the seller. They get to set the price and
and the buyer can take it or leave it. As long as their minimum price is above cost they make
a profit. The buyer only gets hash when the seller is guaranteed to profit an dthe buyer probably
overpaid.
A service like Nicehash is an open market like the stock market. They are just brokers between
buyers and sellers and have no influence on price, the market determines the price. It's arguably
a fair market, if you consider trading bots fair, that pits trader vs trader and the more skilled
(or better bot SW) will profit more.