That isn't true. Like in my situation, she's hot, probably hotter than I deserve, but I don't wanna fuck up a friendship due to a one night stand.
You'll hit a threshold before the Friendzone barrier breaks. It'll come down to:
a) Risk the friendship for something more. (live without regrets)
b) Keep the friendship knowingly accepting that you "might have" had something special. (live with regrets)
Then again, there's the rare option "c" ... There's something just about her that just doesn't seem right anyways.