there is no guarantee doing holding would make profit. As happened some time ago. The price of bitcoin has drastically decreased so that many people holding hold feel disadvantaged. Whereas they can sell bitcoin when the rates reach 2800USD. Currently only in 2000USD, this is what makes all things uncertain.
but i think we have good experience of long term investment. those people who have invested money for long term then there are more chances to make money in log term investment. for example those people who had invested moneyi in previous year or month, they have already made good profit. and am still confident that those people who have invested money right they are also getting good profit.