because selling at any time results in orders of magnitude loss several years later.
its hard to trade orders of magnitude profit over that time.
eg sell under $1, jumps over $1 forever, buy back in at $100, because you were waiting for it to drop under $1 again.
how can you trade that?
sell under 10K, jumps to 15K, never goes below 10K, you wait and have to buy back in at 50K or 100K.
how do you trade that....?
and that is the history of BTC.
The scenario that you are suggesting in your post can happen but you can also profit from the ups and the down of the market, someone that got bitcoin at 2400 and sold and then waited when the price touched 1800 and bought bitcoin got 33% more bitcoin and if he sold at the current price of 4300 could have gotten earnings over 138% its starting capital in less than a month and if the price goes lower, which is likely, then he can get even more profits. its hard to trade orders of magnitude profit over that time.
eg sell under $1, jumps over $1 forever, buy back in at $100, because you were waiting for it to drop under $1 again.
how can you trade that?
sell under 10K, jumps to 15K, never goes below 10K, you wait and have to buy back in at 50K or 100K.
how do you trade that....?
and that is the history of BTC.
? This is the reason make many people want holding Bitcoin for long term and enjoy profit. 
)) as you can see if you buy a Bitcoin when it cost about 600 - 800$/ Bitcoin but now it more than 4400$/Bitcoin that mean you earn more than 3000$ only with holding bitcoin and sell them at the right time 
