My advice to them is that if there is anything else they can do, do it. Being a professional actor is miserable. The odds are it will fail entirely; most of the remainder will barely make subsistence.
Much of what I do is to provide a place for people to be genuinely creative in ways that they couldn't afford to if their living depended on it. We get to take artistic chances that please us. You don't get that if your livelihood depends on it.
A few people have taken my advice and concluded that they needed to do this. Some have had minor successes. Good for them. Others tried and discovered that indeed, it was not fun and not good for them, and they left. None, fortunately, are starving, convinced that persistence is the key to success because they read it on a motivational poster.