It's frustrating to hear this view being shared flippantly after such a long time. It's of course fine to have various views as to whether or not the project is worthwhile or not, but a blithe dismissal as a "vanity project" means you've not really seriously considered it.

I'd encourage you to read this article (from a few years ago now, but still applicable) which I think is a good summary as to the importance of the project generally. Even if you disagree, it will hopefully lead to more informed discussion: https://www.independent.co.uk/news/uk/home-news/hs2-logistic...