Some people pay for ads even on their social page, they do pay for those ads so that their content can appear frequently for visitors and also for their content to appear easily on search. Some of them that are making money via freelancing also spent some money to build their page. What I just feel is not right is the misleading idea of gambling that some of them try to pass to their audience.
It is correct that people who promote gambling sites invest their time to write content or invest money to take the content and they promote themselves the content or hire representatives which costs them as a result they might be able to earn money for affiliates. They are investing time and money that doesn't mean that they don't/can't mislead their audience. It can be misleading if the site has negative issues eg: scamming or something like that.