I personally don’t understand how people in some cultures or countries, may celebrate the life of a person so soon after his/her death.
I couldn’t do it. At the beginning I feel pain for the loss. Not in selfish way, as @moodyblue83 mentioned (I can understand the way (s)he sees it, but I also feel sadness for the person who passed away.

I needed six months to accept my dear dad’s passing. Of course, he’s not conscious anymore, he’s not here but I wanted the best for him. I wanted him to enjoy life and take the best out of it. I suffer for him along as I suffer for his loss and what he represents to me.

I neither understand why people celebrate a person who passed away’s birthday or anniversary of birth since this person is not here anymore.