I heard that investing in bitcoin is dangerous. How true is this?

If you don't want very good profit in very short span of time then investing in BTC is dangerous because BTC is that superstar of cryptocurrency world that is always going to be in lime light. Millions of investors declared BTC an asset which would be used by future generations. Although in the first month of 2k18 the valuation is deflating but the future with BTC is always very safe and secure.