I believe that diversification in the field of investment is a basic common sense. The high volatility of bitcoin is accompanied by high returns and high risks, and both real estate and bank bonds are low risk and stable investment. I believe it will bring more possibilities to your investment. If real estate is in crisis, maybe you can make up for losses in bitcoin, which can make your investment more flexible.
Well reducing the risk by sticking to something that has higher risk is a lot more riskier for me :p I have noto problems with having a huge bulk of my portfolio in btc, but not having any other assets to fall back on in case things go unwanted is something also to consider. Bitcoin's value is subject to speculation and it can go anywhere depending on how people think about it.