What kind of profit do you mean, is the decline giving some people the momentum to enter the market. In 24 hours bitcoin has experienced a slight decline but if you look at it previously it was actually below it so that in the previous few days it had a slight increase. If you say for the long term it might be true that people can take steps to buy when there is a decline but the decline that occurred in 24 was actually small, so the accumulation of small amounts will not provide maximum profit for the process. Conversely for traders involved in futures and their profits depend on how they open entry positions.