A list of big amounts of factors determine the price of Steem.. One of the important factor is Powering Up and lowering the supply of Steem in the market for buying and selling.. So when most people powers up then supply available for sale is low making the price go up.. but when price goes up big whales starts powering down.. and when they start selling hundreds of thousands of Steem all together in one go the price goes down.. well that's just how I interpret it.. that's why Steem is undervalued.. Moreover SBD is highly favoured by the Koreans to make instant payments because of its fast and zero fees transactions making SBD more favourable than Steem.. but again as I said there could be some other reason why Steem is undervalued which I might not be aware currently