We don’t have generational wealth to fall back on when we don’t succeed, thus making it more difficult or impossible for someone in the lowest class to make it as a top billed actor.
Neither did Olivia Colman: Her mother was a nurse, her father a surveyor. Decidedly middle class, but she was not born into wealth, nor the children of famous people. She studied to become a teacher, before she got a few small roles in British TV and build a career out of that. She went the long way.
She is not from the lowest class, or a top billed actor, to be fair.
I don’t have generational wealth like many of these actors do. There’s also a lot of nepotism and if you are not an industry insider, it’s near impossible to even meet people who have connections in the industry.