Nothing is 100% and so many things can go wrong anytime. If you are invested all into Bitcoin or whatever else you can realisticaly end up nulled. Altcoins, precious metals, land, enumismatics, rare or even unique stuff with constant demand are a nice way to hedge against total loss. Good portfolio is one where person is well diversified within and out of some sector, with very stable to very volatile investments where more attention and money is put into currently stable stuff. But whoever dismisses very volatile investments should not expect to ever see 1000% or higher gains.