Here is a lesson everybody could learn: I am not an influencer. Do not ask me to influence anybody. If I had control over what people did, I would have a nice home in the country, never have to do the dishes, and my kids would be well behaved at all times.
This is not the case. People are gonna do what they want no matter what anybody else tells them. The more they are told they can't, the more they will push away and try to prove you, and everybody else, wrong.
The most I think we can tell those we love is "This is how I feel about the situation and what I would do if I were in your shoes. However, you are grown and have to make your own decisions, so I will support you."
In the end, I honestly believe that support, love, and knowing that you will help them pick up the pieces if the foundation cracks or falls apart, is all we can really do.