The survival instinct is the most basic drive in any living thing. If the idea of ceasing to exist truly doesn't make you uncomfortable then it might be worth talking to a professional...
I don't fear death, I fear the process of dying, I wouldn't want it to be painful or slow, but not existing, that I do not fear.
Yes, the cosmos remains intact even as the ego dies. But it seems dismissive to say the ego is less precious and can be calmly dismissed because the eternal universe which gave rise to it persists intact. It gives me no comfort at all to know that the eternal fire will always burn, and everything that constituted my fleeting ego will always exist as well. My self-awareness will be gone forever. That is a real and impending loss, although i'll be blissfully oblivious to that loss soon enough.
So I don’t usually believe what people say about themselves on this topic. Unless they’re quite old or lived through cancer or some similar situation where they had to confront their mortality, I won’t assume they know how they truly feel about their death. It’s just an idea when expressed with words, and simply thinking about it may not evoke real emotions.