I've always found "Buy low and sell high" to be one of the most infuriating axioms in trading (up there with "control your emotions"), and not because it's not true. It's because it's vague.
Indeed, it's only smartasses looking at the chart afterwards who will say "you should have bought low".
There is no low. The BCH was high when it was 600. It was already crazy high compared to weeks ago. Of course smartasses are gonna tell you that "it was low".