There are many places where you can store infinite data "in the cracks" so to speak.

Someone created a wiki-based filesystem that stored data as random wiki pages (wikipedia and other wikis).

They automated account creation, and then created pages with large chunks of base64 encoded encrypted content.

Doing this stuff doesn't make you clever, it just makes you an asshole.

There are also places where you can store large amounts of data for free, not even in the cracks.

For example, dockerhub lets you upload large bundles of data (gigabytes of data with no issue) for free. It's s3 backed, so effectively it's free s3 storage.

Image storage sites, like imgur, let you upload tons of images, and you could easily store data steganographically (edit, typo fixed).