Last week the rates on lending dash on polo were extremely high due to the sudden increase in value of dash and the subsequent massive shorting. Rates were at 2% for quite a while. Imagine 100 dash loaned out on 2% interest for 2 days. That's interest per day, not per year. It would take six times as long and ten times as much capital to make the same amount with a masternode.
I still have 80 DASH loaned out at 0.8% per day from that time, its building up nicely thank you.
Unfortunately, the rates have sunk back down to the normal, about 0.01 - 0.02 per day. IMO, it's only interesting for some spare dash that you can accept being locked away for a couple of days.
So there is definately a case for making money out of lending dash on polo but, as people above have stated, there is risk. There is risk that polo goes broke or gets hacked. Polo is a big target, you can be sure that people are trying. A masternode is a lot safer, depending on how good your personal security is.
I think shorting, or going long, leads to a more stable market, with less dramatic peaks and dips.
And finally a tip: if you are going to margin trade, then make sure you check the lending rates! The default rate in the box on Poloniex is 2% per day, which is way too high. And keep checking them ... some idiot still has 80 dash borrowed at 0.8% for almost a week after the rates have dropped back to 0.01% or less. 0.8% per day is 292% per year. 0.01% per day is 3.65% per year. Very different.
