You're substantially over estimating the thought capabilities of over 99.87% of market participants, I would really struggle to believe this overwhelming statistical majority even understand which way to hold their toothbrush.
But even if a small subset were able to do this elementary arithmetic, and gave 35% chance to "2000$ in 5 years", they should be buying those coins for sale at 400$.
As for waiting for cheaper coins: one must compare the plans (A) "buy 1.00 BTC with 400$ now, wait for price to reach 2000$, sell" with (B) "wait for price to drop to 350$, buy 1.14 BTC with 400$, wait for 2000$, sell".
Assume that plan (A) has 35% chance of success within 5 years, that is, of price reaching 2000$ in 5 years. To simplify the math, assume that the only alternative to success is total failure; that is, the price will suddenly crash to 0$ before the 5 years are over, without ever reaching 2000$. Then the expected profit is 1.00*(0.35*2000 + 0.65*0) - 400 = 300$.
Plan (B) will have smaller chance of success than plan (A). Let's say that there is a 20% chance that the price will never get as low as 350$ in the next 5 years; in that case one will keep holding the 400$ in dollars to the end. If the price
does get down to 350$, the chance that it will recover and then rise to 2000$ must be less than 35%, because it has to climb 50$ more, in a shorter time. Say that the chances are only 30%. If again we assume, in the second case, that the only alternative to reaching 2000$ is sudden crash to 0$, then the expected profit will be 0.80*1.14*(0.30*2000 + 0.70*0) + 0.20*400 - 400 = 227$.
This math is oversimplified, of course. For a proper analysis, one should consider more possible outocomes, besides success and sudden crash (which I
don't think is likely), and other strategies besides (A) and (B). The point is that the advantage of waiting for a lower price -- to have more coins to sell in the end -- may be negated by the risk of the price going up, and never reaching the expected low price; and by the smaller expected value, if the price does get that low.
Poll
