I largely agree to most of what you said here because a Bitcoin investor should only be thinking of investing in Bitcoin true his discretionary income, any money used to invest in Bitcoin outside his discretionary income spell trouble for the longevity of his Bitcoin holdings.
If an individual feels like investing aggressively in Bitcoin, it should only be done from his reserve funds not from the money meant to take care of his basic needs or his emergency funds.
Actually, if the path is investment, of course the capital specifically to run the investment must be there and prepared from the start so that it can be used immediately for that, especially if what you want to buy is Bitcoin where investors will be much better if they can buy it earlier. And for smart investors, I think they will make their own sorting of their money when they want to do something bigger in the long term such as investing in Bitcoin so that the funds that are sorted will really be used for one purpose only and will not be mixed with others because other sectors are also prepared specifically by themselves.