When investing you should always diversify in order to reduce risk, and determine what your investment goals are and your timeline. For example a young person in their 20's may have a 40 year investment horizon (aiming to have a good retirement fund), whereas a 60 year old may only be looking the next 10 years ahead. Other people may only want to invest for a few years depending on their investment goal. An older retired person is likely to want income from their investment whereas a young person wants capital gains and doesn't need investment income if they have a job.
Generally each type of investment vehicle as a different risk/reward/timeline profile. In the case of bitcoin, it can be considered high risk with a very high potential reward. It is the type of technology that could either revolutionize the world financial system or become a failed experiment (or killed off experiment by regulators/governments). Bitcoin does not pay dividends, interest or rent but does have a high chance of large capital gain.
Bitcoin proponents believe bitcoin could one day be worth $100k per coin whereas other believe bitcoin will fail and hence become worthless.
Therefore bitcoin investment should be part of a balanced portfolio. Portfolio theory would dictate balancing high risk investments with low risk investments. Finding that right balance is the hard part and only clear with hindsight