If it takes me longer than 5 seconds to access the content I'm looking for, I close the tab. Am I alone in this?
I doubt you're consistent with it. You'd probably wait 10+ seconds to post an HN comment for example. Easy to say you'd bounce on a website you didn't care about. That's a bit of a tautology.
There are so many SAAS products now, and it doesn't take much to lose out on potential users. It doesn't really impact my life much because, as you said, I probably don't have much investment in it in the first place.