It doesn’t help that the entertainment industry is primarily run by old white men, who are absolutely obsessed with coveting pretty white women, who are under 25. I’ve never grown used to their crappy, and let’s just say it, rather pedestrian, tastes in women, although I can appreciate that their middle of the road, physical tastes brought us such great actresses as Margot Robbie.
To make it in Hollywood beyond that age, they need to do what many women like Robbie have done, which is amass just enough clout playing such roles, to start creating some of their own, so that they don't always need to go begging to such men to find work. That requires a combination of intelligence, planning, and ambition that a lot of very young actresses don't realize they need to have, before they get chewed up and thoroughly exploited by the industry. And like Robbie they need to bring other women along with them while they climb the ladder. This is how a network of women gets created in such an industry.