This was somewhat common with Brexit; small business owners promoting Brexit, then suffering or going out of business when it actually happened. It's even less excusable in this case, though; the reasons that a hard-but-not-no-deal Brexit (which is what the final result was) are bad for businesses, and particularly small businesses, are often at least somewhat subtle and non-obvious (to the extent that _new_ problems which economists hadn't really predicted are still being discovered), whereas it's hard to imagine something simpler than "making stuff more expensive to buy is bad for people who buy stuff".