I assume you also wear a N95 all the time outside of house, otherwise that's a big hole in your defenses.
There probably is some sort of hole which I'm not considering and it's mainly unknowns why I even believe it to be 1%. If there were no holes I'd believe it to be near 0%.
There's people who go to office, are around other people 40+ hours a week, then come to home to large families, have children that went to school. Offices, schools, things like these probably have the most spread.
Even with a vaccine that has 90% efficacy for preventing infection they would be exposed to the virus more than 10x that I am, and so would have higher chance of getting infected.
I know some studies calculated efficacy from hours spent in a high risk situation.