According to John Bogle, as cited by @Bogleheads, effective risk management is essential for traders, with a 20% market loss being a normal occurrence. This principle is especially relevant for cryptocurrency investors, where volatility often exceeds traditional stock market swings. Traders should assess their risk tolerance and implement stop-loss strategies to protect capital during market downturns, as highlighted by Bogle's investment philosophy (source: @Bogleheads).