Most likely because old buildings are expensive to maintain, expensive to heat, must be refitted for modern lights or communication or have asbestos or lead pipes or don’t comply with modern building standards, such as accessibility.

There is this old cinema from the 1920s in my town that went out of business in the 1990s. Nobody goes to the cinema anymore to fill the 300 seats, it’s a 20min walk away from residential areas and there is no parking nearby. On top of that it needs 30 years of maintenance. Nobody has a good business plan for this building.

https://www.1000libraries.com/blog-posts/why-was-the-old-cincinnati-library-demolished

Not originally constructed as a library. Too hot in summer. No windows. Books would get covered in soot in winter. Flooded. Wasn’t safe for the public to even be in.

Lovely as it looks here, in historical terms 75 years old is last week. My town is demolishing a 117 year old cinema to make way for flats, and nobody gives it a second thought.