I meant physical size, not data size. With one computer with multiple 24TB drives, you can store hundreds or thousands of Blu-rays. To have that amount of physical Blu-rays, you would need a massive shelf - or more likely, multiple massive shelves.
True, RAID is more expensive, but it also ensures your data will keep working reliably - and it's much harder to lose than a small disc. Doubly when you throw backups into the mix.