The problem is people warned him, told him to implement protection features yet he doesn't care
Because he doesn't know. Why would he care if he doesn't know? Why are you careful with fire? Because someone told you? No, it's because you got curious and burned your hand. You learned to care.
"got curios and burned your hands"
That's common sense isn't it

When I started learning electronics, the first thing I did was not starting at the basics, I started learning about safety basics, what-not-to-do stuff like that then I started learning the basics. Safety first!
Anyways, I think we should let him have the lithium cells blow up his face. Should give him a lesson about listening to others and why you should integrate power management in your projects