A lack of sleep creates stress. There are a lot of other ways to create stress. Time pressure, money pressure, conflict, disappointment, home life, and embarrassment all create stress.
When getting into business with a partner, you need to know how they will deal with stress. If this person does not deal well with stress when faced with a little sleep deprivation, especially over something as simple as coffee, then it's a huge red flag.
Imagine that it's crunch time, you're all running on minimal sleep, and you're trying to get a demo perfectly solid so you can either get your next round of funding or sell to interested parties; i.e., there's a lot on the line.
Do you really want this type of person shrieking at everyone in the room because they're not typing fast enough? Do you think that's going to help you and the team?
That is simply a luxury of time you often cannot afford. Who knows when his next explosion could come? Could be in 6 months at crunch time. Unless you're desperate for the help then it's best not to get in to bed with this kind of person - yep based off that one experience.
When getting into business with a partner, you need to know how they will deal with stress. If this person does not deal well with stress when faced with a little sleep deprivation, especially over something as simple as coffee, then it's a huge red flag.
Imagine that it's crunch time, you're all running on minimal sleep, and you're trying to get a demo perfectly solid so you can either get your next round of funding or sell to interested parties; i.e., there's a lot on the line.
Do you really want this type of person shrieking at everyone in the room because they're not typing fast enough? Do you think that's going to help you and the team?