If masks contain spread and everyone wore one, it would lead to less cases.
The problem is that there are not enough masks to go around. But if there were, i would recommend everyone wears them. Just so it would make it socially acceptable to wear one if you are sick.
Few if any people with it know the exact time they become symptomatic and start viral shedding. Everyone should assume they might be sick when in public and could be shedding. With this standard everyone would wear a mask.
Masks work, but needs to be disinfected when you get home. (Using steam. Microwave, a plate of water, mask above the water, 3 minutes is the minimum with steam bags, so let's try 10 minutes without bag.)
So if you are sick, wear a mask. Here in Germany you still get publicly ridiculed for it.