No currency in the world is safe forever. All currencies have ups and downs depending upon the market conditions. Even USD, gold are volatile in nature. Bue due to their centralized nature their volatility can be controlled by the regulating authority. People have trust in both currency and its regulators. Bitcoin is a decentralized currency. It operates on the mutual trust and understanding among its investors. Bitcoin is the most risky and volatile currency, due to lack of central authority no one can control it. Hence it moves sharply on both sided resulting in huge loss or gain in short period of time. Bitcoin are safe in its own security system Blockchain. All transactions are regularly monitored and verified by its miners.