It is not bad for people who believe in BTC and whom have good knowledge about it, because there is no doubt that there is risk in it. Volatility risk and security risk, so if you understand these, you'll know were to set your expectations and also how to safely store your coins. It is also important to know that you should have part of your money in lower risk investment, especially when we are talking about a retirement plan, i.e. bonds, Money Market Funds, etc, so the point is, do not plan for your retirement with only BTC, because it is a high risk asset.