It's a single data structure that contains your entire game though?
Are you asking?
but calling it a "single data structure" is a bit reductive.
No it isn't. It's like a tiny database. Depending on how someone implements it, it could use arrays, hash maps and b-trees. There is no universe where this means a binary that does nothing should be 50 megabytes.
> It's like a tiny database.
No it isn't. It also handles system management and concurrency, basically the main loop of your application.
I also would be cautious of assigning the blame of the binary size onto the data structure on its own.