I don’t like this common financial advice that much: “don’t put in money you can’t afford to lose.” There are too many ways people can interpret this. I like to think of it with more nuance.
Here's the way I prefer to phrase it: "only put in money that you are okay with losing."
If you aren’t okay with losing any money at all, then don’t put in any money. Investing is not for you. Just don’t do it.
If you’re okay with losing all your money and potentially becoming homeless, and you want to put in all your money, then go ahead. It's your life. Stay true to who you are. Make your own decisions.
It all comes down to knowing yourself, knowing what you want, and making decisions based on it. I talk more about this concept in my book. When it comes to investing, specifically, it's about your own risk tolerance and your own goals.