OK, now not pure caffeine, but actual witnessing someone almost die accidentally from a caffeine overdose before. Please look into it first.
We worked in a factory, mandatory 12 hour shifts, illegal 7 days a weeks for MONTHS (labor board violations in the state). We almost lost 2 employees to accidental deaths, one almost overdosed on drugs just to stay alert enough. And one just used caffeine. He took like I can't even remember, but a few Rock star energy drinks, a couple 5 hour energy things, caffeine pills, and a number of other things. Mid shift he was shaking, could feel his heart beating everywhere, he swore he could see his heart beating in his chest. There were other symptoms, but whether factory-related, or drug-related I'm not sure. He was completely terrified (as were we!), he just wanted to stay awake. I can't remember if we had to call an ambulance for him, or if he was given the choice to lie down in an office, but it took a while before he was even able to breathe normally again. He actually stopped taking almost all caffeine drinks after, but one or two energy drinks a day. It was that bad, he would not risk the feeling again.
I mean you're free to do whatever of course. But just saying... from my experience of seeing someone actually OD on it basically, it is not pleasant. The worst part would be if he hadn't reached OD levels yet.