Yes, the person who lost their money made a terrible, stupid mistake... but if you spend more than a moment in/around cryptocurrency projects, you will be sucked in to believing that _the old-world financial system is crumbling, the only way to secure your future is by investing everything into cryptocurrency_ and so "only invest what you can afford to lose" has an implied wink, "I'm only saying this because the old-world system will come for me if I don't!"
I have sympathy for the fool.