Outside of a philosophy class, 'know' takes on quite a bit more pragmatic meaning which is perfectly appropriate here.
And inside philosophy class, I would argue, that the knowlege of the chair your are sitting on, is also not so much more confirmed and solid knowledge, than ones own birthday.
Outside philosophy class, do you not distinguish between those things you have personally experienced, characterising them as things that are known (to you), and between those things that you've seen on a screen or heard, characterising them as (mere) possibilities to you, yet to be experienced/verified?
I'd argue that it is pragmatic and useful to distinguish between 'know' and 'believe' (or 'hypothesise').
But yes, some people do use 'know', 'think', 'believe', 'feel', etc almost interchangeably. I think this cannot help but lead to confusion.