Not a lawyer, but my understanding is that the GDPR is only applicable if a website is engaged in the "offering of goods or services" (regardless of whether a payment is required) to data subjects within the EEA, or are monitoring the behaviour of data subjects within the EEA (Article 3(2).
Since the forum isn’t providing goods nor services, they don’t have to.
Seriously though, if you don’t want to be here, stop logging in or do the password scramble like LMU suggested. It’s really not that difficult...