It defies common sense to not wear a personal mask. Like donating your six shooter to an outgunned military. The marginal benefit to you is so much more than the marginal benefit to them.
More like donating your ballistic vest to a military that's expected to win eventually but with heavy losses. The marginal benefit may be low due to the sheer scale of the problem they're facing, but it still might save a life—and what if every American made a mask and donated it instead of wearing it themselves?
It's also possible—likely, even—that the severity of the disease in an individual is correlated with the magnitude of the initial infectious dose, and healthcare workers without effective PPE are going to be most at risk for high doses, which will act as a multiplier on the benefits of PPE usage for them. In the analogy, one might compare this to the chance that a stray, tumbling bullet fired in a high arc by the enemy will hit you while you're trying to buy groceries, vs. the chance that a soldier on the front lines will be lethally wounded by a deliberate shot. Who needs the vest more?
As noted here^[1], this is all very much up in the air, but the more I think about it, the more my brain rejects the marginal benefit argument as an illusion. Healthcare workers are on the front lines, and by most accounts it's their labors that'll cut the mortality rate from 10+% to ~1-5%. They need all the help they can get, and the rest of us need them to stay healthy and able to do their jobs.
