For normal person? They are mostly useless. Only for people, who are already sick, to stop them from spreading virus further. Wearing mask by healthy person doesn't make sense, because there is not much to stop viruses with coming in contact with your eyes. You are always a scratch away from bringing those viruses into your body, negating any benefit from mask. And most of mask, you can buy currently are not dense enough to capture viruses.
OP is correct, unless you are sick or medical worker, you don't need mask. Don't buy them, hospitals need them much more than you.
Is WHO [1] good enough source for you?
[1] https://www.who.int/emergencies/diseases/novel-coronavirus-2...