Bitcoin is a very good investment and one of the best in the world right now, Bitcoin is a very good asset however I really don't support someone having Bitcoin as his or her only investment but if you are still growing your Bitcoin investment I don't think is a good idea to diversify to another investment immediately because you will lose concentration at some point and if you are not careful you will end up losing your Bitcoin investment and the other investment you decide to diversify into, so is better you focus and build your Bitcoin investment to a certain level and then you diversify to another investment.
I'm not saying one should diversify because I don't trust in Bitcoin is because having only one investment is not a good one, no one can tell what may happen in the future so having different investment will help you keep your wealth going, there are some people that where very rich before but right now they are poor and the reason why they are now poor is because there only investment failed, so is only better to have different investment it gives you more money and also give you confidence in life.