This is really funny though because you are advising people not to sell their bitcoins but you have sold yours for some shopping even when you know you sold at lost due to the price of bitcoin now (though i don't know the price you bought) but it is very wrong to sell when the price of bitcoin is falling just to attend to an immediate need and if i were to be you, i could have considered borrowing to sort out your shopping because i can see you don't have emergency funds in case of situations like this and that is why keeping an emergency funds or making out plans to keep funds for unavoidable events is also important because it will make you not to take regrettable decisions in the future just like the one you took and you are already regretting your actions. It's not like we can't sell bitcoin to attend to an immediate need but let it be done when we have already gotten a big portfolio and when okay with the amount we have accumulated.
He didn't have funds for his urgent needs, so he had to sell bitcoins. So many people say, don't invest more than you can afford to lose. Means you invest in Bitcoin and forget it, and keep funds for your urgent needs so that you don't have to sell Bitcoin in any situation. If you have an emergency fund, you can hold on to the investment in any situation. So we need to plan long term before investing, if you hold for short term then you may not be profitable. Now we don't know whether the person who sold the bitcoins was in profit or loss. Maybe he will regret such act in future. If you don't want to regret in future, then buy again, keep fund for emergency, so that you can hold for long term.
Yes one should be careful with their investment in the crypto market. We shouldn't invest our kitchen money in bitcoin as we never know when we may be needing that money and at what price is Bitcoin at that time. Chances are that one may have to sell in loss if prices are lower.
Another scenario is not to take loans in order to buy Bitcoin. You have to return loans by selling Bitcoin and you never know the price of Bitcoin in immediate short term.
Yes, we should not invest money that we may need very soon. Especially if it is done with daily expenses, or if it is money for an important work that you will need after a certain period of time (6 months or 8 months or 1 year). The basic rule of investment is, invest only that money, which even if lost, it will not have a big neg impact on your lifestyle. And an investment must be for a period of more than 8 years, because the minimum period of a long-term investment is 4 years, but if you can hold your investment for more than 8 years or 10 years, then the possibility of profit from it will be at the highest level.
So use the right money to invest, also investing in Bitcoin with a loan can be more dangerous. Because after a certain period of time, you will have to repay the main amount of your loan with interest, but when the loan term ends, and if the value of Bitcoin is low at that time, you will have to sell the holding at a loss, but then it will become difficult to repay your loan. Because you have to pay back the amount of money you owe, both "loan" and "interest" and You did not get that amount by selling your Bitcoin investment. That is, you will not gain anything by investing and holding it for a certain period of time, but rather you will have to repay your loan with money from your pocket.
That is why investment should always be long-term, and risk management should be done properly. With an eye on the future, You need to invest carefully using the right strategies. Only that money should be invested, which if lost, it will not have a major impact on your personal financial situation, and the most important thing is that, regardless of market fluctuations, your investment must be long-term, for more than 8 years or 10 years, and you must invest regularly. Because when your investment is long-term, your profit potential will be at its highest level.