I hate it when I do that too (I was born in 1975, which is clearly unacceptable).

However, I have seen 2001 five times at the cinema over the years, during various rereleases (twice in 70mm, once in 35mm, and twice in digital 4K). It is regularly rerereleased (at least it is here in the UK). Both of my children had their first viewing in the cinema rather than TV. I insisted on this. True love waits, and all that. Afterwards, they thanked me. :)