“Fair use” isn’t just determined by whether or not the person reproducing the work makes a profit though, because even if the person sharing the work isn’t making any money it doesn’t mean that the act of sharing it isn’t impacting the person who made it.
For example, if someone self-publishes a webcomic and makes an income from ads on their site, then sharing their work in other places can cost that person ad revenue. Or in this case the Pepe “brand” is damaged by association with racists, so the artist may lose licensing opportunities he might have otherwise had with the character.
A lot of the copyright infringement that happens online isn’t legally protected under “fair use,” it just isn’t prosecuted because it would be impractical to try chasing down every stupid meme people make out of someone else’s content.
