You weren't unable to attend anything. You had an option to attend the event - get vaccinated. You chose to not attend the event. The only thing "keeping you" from it is you.
Maybe your next thought is the vaccine makes the conference safer. Let's play Choose your own Adventure. You have to sit next to someone on a crowded airplane in economy class for 3 hours and this person loves to talk. You get to choose that this person is either a) vaccinated, or b) tested negative for covid every day for the past 3 days. Which do you choose?
It's fascinating and scary that fear has led our society to let segregation creep in under the guise of public health.