Perfectly understand most experts said that face masks should be used by one who falls ill instead of healthy one.
I did same thing that I didn't wear mask during SARS. But I chose to do now -
1. Environment changes - there are lots more people around, places are getting crowd, hard to say everyone has the same high level of hygiene standard. Spitting getting more commonly seen again; sneezing / coughing without covering mouth...
2. Longer unknown period - are you 100% sure if you are healthy? Even if you are tested positive under this virus, you may not have any symptoms. Do you wanna protect people around you?
All in all, wearing face masks or not is a personal choice, same as whether taking vaccine or not. Same old argument.