Damage to his reputation and fanbase. He has a rep for being a pretty cool guy who makes fantastic games. Now he's at risk of losing some of that rep because of the way people reacted to a few things he said and did that, honestly, I believe have been entirely misunderstood.

This isn't the first, second, or even third time a Binding of Isaac release has had massive glaring bugs and achievements and items that failed to work or show up. Vanilla, WotL, and Rebirth all had massive issues. The only difference is that this time the community expected a big Lost style puzzle and were reading too much into a bug (the Greed machine 109 bug) from the get-go.

How can 50-odd items just go missing? Beats me. I don't know how they coded this game. But a whole set of achievements did the samw thing last year so I'm not surprised. The saves didn't even import correctly until a hotfix a few hours after this year's release.

So Ed, not realizing this bug had been released, played along with the community and tried to hint that there was going to be a fix for all this if we just waited (hell, he explicitly said he was doing some big bug fixes) but no, the community literally read hidden meaning into every single word he said. Then once it was realized the bug was there and then fixed, Ed thought "Hey, wouldn't it be funny if we released this patch at 109 hours because the community is going crazy over 109?"

Apparently not. Apparently, because he released the fix with all the remaining items at 109 hours, he's mad about the Lost being ruined last year, wants to punish his entire fanbase for it, and would also describe Hitler as an okay guy.