You are absolutely correct. However, it is not the technical structure of bitcoin that is a problem...it is human nature. Humans need to adopt bitcoin, and it will be a while before that happens at critical mass.
Today, and for the near foreseeable future, it is a good approach to have a diversified portfolio. I do not mean in the stock market, but in small businesses, precious metals, bitcoin, and keeping only the minimum operating cash in dollars.
The best investors are able to adapt, and maneuver through multiple systems to achieve their goals, similar to how on Earth, the strongest species are not the strongest, or fastest, they are the most adaptable to the environment.