Coronaviruses seem to be everywhere.  They are on both sides of your mask and even (likely) in your body already.  I'm not an expert on masks or filters, but it seems to me there are four basic possibilities.

1. The mask keeps the virus out.

2. The mask keeps the virus in.

3. The mask biases the likelihood that the virus will move from one side to another.

4. The masks are utterly worthless.

Possibilities 1 and 2 have been claimed at one time or another.  We have been told to wear the mask to protect ourselves or to wear it to protect others.

Possibilities 3 and 4 have been less directly addressed.  The recommendation is to wear the mask because it might help.

But does the mask actually keep the virus from moving from one side of the mask to the other?  Let's pretend the effect is absolute, just for a moment.

If the virus is kept on the outside of the mask (option 1), then it isn't necessary for everyone to wear a mask, at least not to protect others.  People can be protected by wearing their own masks.

If the virus is kept on the face (inside the mask — option 2), it's likely that you breathe it in and provide a better growth environment than it would find on the outside.  As it proliferates, you may get sick, whether you are symptomatic or not.  This would correlate to increasing numbers of cases in areas where masking is prevalent.

Possibilities 3 and 4 are just cases 1 and 2 with a lower probability that the virus will be kept on whichever side of the mask it's currently on.  You can still get just as sick or stay just as healthy.

Being forced to wear the mask risks your health in three of the four scenarios.  In the fourth (option 1), other people can protect themselves.