What if a feed-producer, after some period of time, pushes a really low price feed (because of bad intent or software error), then she, or someone else, borrows huge amount of the asset from the blockchain with almost zero collaterial and sells it to the market devaluating the asset and getting all the buy orders? Are smart assets more safe from that perspective than regular UIA? How can a trader (or a smart asset owner) be sure that the price feed will be correct in the future? And is it actually safe to add a feed producer you don't know?