Why would I want to keep BTC in my investment portfolio? That's most hyped and quite overvalued coin I'd say.
There are other more technologically advanced coins. Is it because of "digital gold" and store of value properties?
Holding bitcoin can make us earn more money than we expect . Some other crypto users hold their coins and tokens so that they can gain more value of the token or coins they hold. In terms of bitcoin , they hold it as long as possible because they are hoping of its price would still increase.