This is the key question here, am talking about the bold words in your statement, because what I have observed about Bitcoin investment is that if truly you have a plan of buying and holding for a very long period of time, and you truly trust in the capabilities of Bitcoin rallying back no matter what, or hoe dip it fell, you wouldn't even blink or even think of selling off your holdings if you invested with a money you can do away with for a very long period of time, because you know that you are not needing it anytime soon, but because any emergency situation can arises in the the future, that's why we make sure to make provisions for emergency funds, so that we wouldn't have to temper with our holdings due to emergencies.
Those who are interested in investing for the long term will definitely be able to accumulate it for the long term if they have a regular income source. Those who have regulars income will be able to maintain Bitcoin for the long term and those who do not have a source of income will be able to maintain Bitcoin for the short term but will lose the ability to maintain that money later.
You are mixing up things a lot in your comment because I don't know how you came to the conclusion that those who do not have regular income cannot invest in Bitcoin for long term. Even without a regular cash flow, you can purchase Bitcoin and hold for a long time and you can even work out your Bitcoin accumulation in such a way that you will maintain regular buying even with irregular cash flow, everything boils down to making expanded estimation of how your finances do come and planning accordingly. You can be doing business that bring in money sometimes two months time and other times six months time, you just take the extreme case which is the six months time and calculate your average income within that space. Let me be a little specific, if on the average you have cashflow of $20k in six months time and in some cases you have same amount in two months time, you can do your calculation with the six months cash flow. Lets say your basic needs for the six months will be settled with $10k, you can decide to invest $6k into Bitcoin at $1k per month DCA while using the balance of $4k for emergency funds. If the cashflow takes less than the six months to come in, you can double down on your accumulation since the funds for your basic needs will not change.
No doubt having a regular income makes the entire process easy since you can do all the calculations with ease but that does not mean that without regular income one cannot maintain steady accumulation of Bitcoin. I believe my explanation will give you a little idea of what I'm saying even though I might not have put it excellently well.