Help with selling old gambling niche domains

Hey guys I want to request some help from the more experienced domain flippers. I have a portfolio of old gambling domains all 15+ and the oldest one being 22 years. I think the domains are pretty good for the gambling niche - however i did not get a single lead for selling them. Can you please give me advice like how to actively market them because sedo and aternic did not go well for me

Thanks to everyone in advance!