Profitability Depends on Sales

Your profitability depends on selling.
Selling is a secondary decision based on the price at which you bought.
In fact, the idea of completely predicting a swing—buying at the bottom and selling at the top—is fundamentally flawed.
Because you're chasing a low-probability event; guessing correctly is itself a rare occurrence, akin to gambling.
Pure investors seek stable profits, not gains through gambling.