No matter how many bitcoin you hold you can still misuse the money, so we should understand the concept of Richness and Wealth.
So you consider holding Bitcoin as saving and want to invest the profits from Bitcoin into something else?
Saving is what you save in the fiat like you save $100 a month in your bank account and not utilizing the money on something else will make you poor because the value of fiat depreciates due to inflation and the actual purchasing power of $100 may worth $90 in the one-year time frame if the inflation rate hits 10%.
Bitcoin also comes under investment cause its value is volatile and I don't deny that you could invest the profits into something else because 'don't put all your eggs in one basket' rule can be applied to minimize the loss.
Most of us see Bitcoin or crypto as an investment so if you are saving your money in Bitcoin, it would basically be seen as an investment for most of us.
And I do agree that no matter how many Bitcoin, crypto or assets you have if you misuse it, it would all just be drained.
We've seen so many successful person or wealthy person in the past who are now broke due to their lack of fund management.
Misuse of their wealth by spending too much on luxury items, drugs or vices, gambling and other forms of addiction.