Well the point of this Offer is that you get it cheaper than the SP that are already on the Account. So if you Power down you will get your investment back + the 10 % + the interest you can make on the steemit platform . The account itself is just a bonus but not really that valueable
I know that 10% is the most obvious benefit,,, but in reality, you probably only get 7 or 8% after the fees and exchanging it back, if you get the best rates. What I am saying is that that is a small benefit for the risk attached (for example the account passwords and private keys are all in possession of the user so you could change the password maybe but I believe not the private key?).
And if you want to use long term you already are stuck with the old posts so you have the identity of the user, not your own. So basically, it is as you say for 1 liquidation of account. At a 6% profit maybe.