My catalog is 32GB, while the Previews file is 158GB. The image count is 198,000. The catalog file seems large in comparison to what others are discussing. Welcoming any and all insights.
I'd guess that catalogue size will be influenced by how much meta data you add, virtual copies, number of collections, book projects, map data, saved prints, etc.
Similarly the preview folder will vary with size chosen, quality and if you discard 1:1 previews after use.
As another data point;
33k images, LR catalogue 900kb, previews 85gb
In that context. 158gb of previews for 198k images seems positively frugal ;-)