The people of that era all went through hardships, and they hope their children have stable jobs, rather than becoming actors, whose future is unpredictable. Most importantly, they don't understand this industry and fear their children will suffer. Though usually, his third uncle and aunt seem to disdain Ruan Lei, there's no way they wouldn't truly care for their own children. They're afraid he won't have a future and will take the wrong path. After all, compared to becoming an actor, getting into Qing University and then finding a job is a much clearer path.
But similarly, for Ruan Lei, this is indeed his life. He is not an accessory of his parents; he has the right to decide his own life.
If he chooses the path Ruan Jianjun picked now, perhaps his life would indeed be very smooth, but it would be filled with regret. He'd probably be tormented and regretful whenever he thought about it in the future.
