Yes, in order to invest in Bitcoin one should not invest more money than one can afford to lose. Now if you invest more money than you can afford to lose then it will be risky for you to hold the investment for long. If you invest with what you can afford to lose then you don't need to sell bitcoins for urgent needs. Besides, money should be saved for emergency use. Now I never invest more money than I can afford to lose. I invest as much as I can. Besides, I have a separate fund for emergency needs. I invest safely, because I don't need to sell bitcoins for urgent needs. However, the price of bitcoin has dropped a bit so no one will be disappointed here, buy and hold bitcoin.
It is absolutely safe to invest money that you can afford to lose, that is, unnecessary money. It is best to invest the money that you have left after meeting your monthly needs, which is completely worthless or not necessary for you. If you are investing with the necessary money or the money that is incomplete to meet your monthly needs or the money that you will need before reaching your investment goal in the near future or in a few days, it is not safe to invest with that money and this investment is questionable in the long term.
You definitely do not want to keep your investment at risk or questionable in the long term. Investing with the ability to lose means that you are planning or managing your investment with long-term investment protection. Starting an investment is easy but making it successful is difficult. That is why you need to give equal importance to long-term planning along with investing. Holding it in the long term is the most important and difficult task of investing. You need to focus on this and try to make the difficult task easy.