You speak like the risks are the same. They aren't. Your statements don't talk about how the risk change with vaccination - and change even more when more folks are vaccinated.
If you are vaccinated, you are vastly less likely to get the infection you are vaccinated against. It is kind of like car accidents - you are vastly less likely to be in any sort of car accident if you are walking (vaccinated) than if you are driving a car (unvaccinated). Most folks will be protected.
Since most folks will be protected and won't get the disease, it means that - with enough vaccinations - the risk for those who don't get the vaccine or who are unlucky enough not to have full effectiveness are more protected as well. This situation is more akin to most folks taking public transport instead of driving cars: Since there are fewer cars on the roads, everyone's risk of getting into a car accident drops significantly.
The number was measured by giving a placebo to X number of people and the vaccine to X number of people. Then you find out that Y number of people with the placebo got COVID, and Z number of people with the vaccine got COVID. Compare Y and Z to get the effectiveness. I think X was like 10,000 or more.
If you are vaccinated, you are vastly less likely to get the infection you are vaccinated against. It is kind of like car accidents - you are vastly less likely to be in any sort of car accident if you are walking (vaccinated) than if you are driving a car (unvaccinated). Most folks will be protected.
Since most folks will be protected and won't get the disease, it means that - with enough vaccinations - the risk for those who don't get the vaccine or who are unlucky enough not to have full effectiveness are more protected as well. This situation is more akin to most folks taking public transport instead of driving cars: Since there are fewer cars on the roads, everyone's risk of getting into a car accident drops significantly.