Reminds me of a conversation I had with a friend from academia.
I'd been chatting about a mutual acquaintance who was behaving a bit oddly by normal standards, continually working very long and strange hours and focusing very hard on their startup. The conversation ended something like this:
"Yeah, I wouldn't be surprised to find out that $friend has hypomania or something like that."
"Oh, really? Have they been diagnosed?"
"Diagnosed? Hah! In startupland, we don't say 'diagnosed'--we say 'funded'."
There's a spectrum. It generally goes something like Hypomania -> Mania -> Psychosis. (Though this isn't very accurate in the general scheme of things; you can be psychotic without being manic, and mania often incorporates some degree of psychosis.)
It can be pretty hard to draw the line between a "go-getter, ambitious, type A" personality type and someone experiencing hypomania. I think a lot of people out there lead successful and fulfilling lives while commonly in a state of hypomania.
> Terry ... works hard, has a clear vision for what he wants to do, and makes it happen.
Mania is a double-edged sword. To not let anything stop you from your goals is to be unable to doubt that your goals, or the assumptions upon which they are based, are crazy. (This is an odd thing to ponder upon, as an entrepreneur.)
There's a rising cultural understanding of what it's like to live with depression—to doubt everything, especially yourself. There's very little cultural understanding of mania, mainly because it's a much more "obvious" problem that quickly marginalizes the people affected, rather than leaving them exposed to society.