Ignorance is indeed not an excuse. Influencers should know that they are public figures and alot of people trust and look up to them. They are expected to be careful of what they endorse and what they reject so they do not mislead their fans who trust their judgement. This is the responsibility that comes with their job, that is why they have only one duty which they owe their fans, which is to make thorough enquiry to be sure they are promoting genuine products and services. An influencer who blindly promotes an illegal or scam casino should not be pardoned for any reason. They have no reason for not performing due diligence by researching the casino very well.
It's extremely easy to influence (and manipulate) people. Youtubers, TikTokers and generally public figures are people of influence, having a large audience creates major leads to your advertisers. It goes without saying that your number one priority should be to protect the people that have allowed you to be what you are today. Unfortunately though, it's quite common to put money first, and what mentioned by the OP is often the result. I've also seen some concerning articles regarding beauty influencers who were promoting unsafe products, ignorance isn't an excuse, especially when there are health concerns.