Yeah, I thought they looked a bit odd - even before the forum decided to cache only half the picture - didn't want to call anybody out.  Did I mention yet that NDAs suck?

It's 'risky' in terms of getting a positive financial ROI.
I.e. you pay X for a miner, and after t time you get Y in return, where Y < X.  OR If you would have bought BTC for X, then after t time you get Z in return, where Z > Y.
( There's also fire hazard risks, with some miners, but I don't think that's what they meant )