[Leaky]

social network sites don't even use 1mb for posts of text, that's a post of 1048576 characters if you are using powers of 2 standard, or 1000000 if you're using powers of 10 (MB vs Mb)


image posts i can see reaching a megabyte with megapixel cameras being so common these days (1 megapixel = 1 million pixels, assuming true color format that's 24 bits per color/pixel so an uncompressed 1mpx picture is approximately 24mb in raw format) but it's unlikely that everyone is posting pictures on every single post.


also HDD space is not called memory it's called storage and storage is extremely cheap and getting cheaper every year.


also your statistics are very inaccurate because you're not taking into account any of the other data that makes a social networking site work such as meta data, layers upon layers of meta data that link everything and everyone together.