Is CEX.IO still profitable? Haven't used it for ages!
it's not profitable since months ago
better to invest your money in another place
What about trading ghs? Buy low, sell high?
I think mining alone is not profitable, but trading the contracts can be profitable if you know what you're doing. As you said, buy low and sell high (or sell high and buy low). This assumes that you are a good trader, of course. I've never tried it but risk-wise, I suspect it would be similar to trading altcoins or BTC/USD.