Initially bitcoin was created for everyone as a solution to eliminating the need for any third-party or financial institution, but due to its volatility it pleases people to see it as a store of value of which has been profitable to a lot of lot of holders. Irrespective of the fact that alot of holders have been profitable from their holdings, it doesn't justify that bitcoin is safe or profit is guaranteed. Alot of people like to consider the merits without considering the demerits and that is why we often hear people call bitcoin scam, or tag bitcoin to those shitcoins probably because of their performance without properly understanding that bitcoin is entirely different any project that seems to have thesame form. So yeah the poor can invest in bitcoin but the most important thing is to have a source of income to fuel their enthusiasm and accumulate using any strategy that suits them but most recommended the DCA strategy. However If anyone wishes to invest in bitcoin without a steady source of income, I'll advise they get a job first because investing without a source of income is easily predictable that they'll end up spending back their investment if problem arises.
Even if they get a source of income then they should also understand the concept of risk management and consider investing only from their discretionary income so they don't make mistakes of using money for other important need to invest in bitcoin and later go back to make withdrawal when they realize their mistake or when the need becomes extremely demanding.
Bitcoin started as way for everyone to send money without needing banks or other companies. But because its price goes up and down much people now mostly see it as something to save money in hoping it will be worth more later and it has made money for many people who have held it. It is true that price has gone up for those who kept it for long time and this makes people sometimes forget about the risks.
Warning you gave people is also good, not to think Bitcoin is always safe or that they are guaranteed to make money. Fact is that its price changes much and only looking at times it has gone up without thinking about times it could go down is bad way to think. This only looking at good sides is probably why some people especially if they have lost money on other cryptocurrencies wrongly call Bitcoin is also scam or think it is same as those less trustworthy coins without really understanding that Bitcoin is very different.
Having steady job and income is most important thing before even thinking about putting money into something as unpredictable as Bitcoin. If you do not have regular income you will be very tempted to sell your Bitcoin if you have any money problems and that mostly leads to losing money. And idea of buying Bitcoin regularly with DCA is good way for many people because it helps reduces risk of buying at wrong time and encourages thinking about it as long term investment.
Your comment is very misleading. Bitcoin price has not decreased but increased. Bitcoin market is very volatile Bitcoin price decreases and increases again. But after the decline Bitcoin always creates a new ATH. We can expect to see a new ATH this time too. In case of long-term investment, the risk is much less. In short-term investment you have to worry about small ups and downs of the market. But in case of long-term investment you do not need to worry about small downs.
It is never right to associate Bitcoin with cryptocurrency. Cryptocurrency does not usually mean a specific currency. Rather, when we say cryptocurrency, we mean all the currencies in the market.
DCA is an investment method. DCA method is not something that encourages us to think of as a long-term investment. Through the DCA method, you can buy at any time and you can buy with $ 5 or $ 10. The most important thing to keep an investment for the long term is faith in Bitcoin. Because if someone does not have faith in Bitcoin, then they may panic and sell their holdings when they see a small decline in the market.
Investing by DCA is not just an investment strategy, it is more reliable when it comes to letting you Hodl for a long term. Even though you mentioned 'Faith' in bitcoin, it is right to say that, but understanding bitcoin is more important than having faith in bitcoin. It is your understanding of bitcoin that would let you understand the benefits of have a 'Limited Supply'. Understanding bitcoin also would allow you understand how crucial bitcoin 'Volatility' is to bitcoin strength. Sometimes we have faith in things without understanding it, this makes the whole task so cumbersome and leaves you out with wishes.
It would be easier for someone who 'understands bitcoin' and invests by DCA to hold longer than someone who has 'Faith' in bitcoin and invests by 'Lumpsum'. It's not just about pushing money into bitcoin, it's about holding for long to avoid running loss when volatility sets in.