[smcl]

It's weird how people mix these up, I think it's due to incorrectly assuming it's related to the verb "to wear".

While we're on the subject - more then and less then are becoming very common due to the similarity in how than/then are pronounced in US accented English.

[nerdponx]

I wonder if this particular mixup is due to people using voice dictation instead of typing. iOS makes that particular error all the time when I dictate.

This particular spelling mixup seems unlikely to persist because people know and understand both words, and it's considered basic knowledge, like your/you're, and I would expect similar memes and derision for people who don't attempt to distinguish them.

[smcl]

You'd think so, but I've when I've brought this up (and weary/wary) people often do the "languages evolve" thing. It's happened before with things like "colour" and "aluminium" so I don't think we can rule it out again.