yes, it is impossible to prop up a currency, at least not for long; there is much talk about the dollar faltering, and even possibly crashing, as it has been propped up for a long time and so is in a bit of a bubble.
. the best thing they at steem could do is to enable easy conversion of their currency to others, such as bitcoin, for little or no cost, and the reverse, conversion of other currencies to steem 'dollars'
. changing the name of the currency from 'dollar' to something else would also be good