Confused by your point?
One of the main reasons masks don't work, is because people using them tend to be complacent. If you work in H&S its a quite well known fact that the more safety equipment, the more relaxed people get and things happen.
Masks, as has always been said, will not protect you from someone who has it. But will minimise people who do have it from spraying the virus, as far, through coughing and sneezing.
I saw a piece on it last night. Wearing a mask, or homemade mask, will not do much to stop you getting it. It will, however, have some benefit if you have it and sneezing and coughing in public (but then you shouldn't be out anyway) and minimise how far you project the droplets.
Then the people who are wearing them, may subconsciously being strict about social distancing, not worry about how they take the mask off, wash hands less, reuse them without washing. It can increase people touching their face, if they have got it on their hands, it will spread that way.
I see lots of people wearing masks, especially home made ones, are constantly adjusting them, then picking stuff up. Or pulling them down to talk.
That said, I think if it makes you feel better to wear one and you still observe all the social distancing and guidance and use it properly, I would say wear one.