I think people sell bitcoin because of their daily life needs, because bitcoin can be exchanged for fiat money but it may be that some users / investors see this as a lucrative investment if it is sold when bitcoin prices are high for profit, also buy again when bitcoin prices low.
Right a lot of people use to sell bitcoin for different reason not one is having the same reason for selling bitcoin as some people buy bitcoin at low price save and sell at high price so it is call short time investment so they sell for profit.
I trust in long time investment for bitcoin, if they will hold bitcoin for couple of years it will be more profit able for them, so to avoid panic selling people should spare some extra money in case of emergency they will not have to sell expensive bitcoin to reach their needs.
