Database Growth Question

[JSmithOner]

I'm making an editor with nested objects hierarchy and I am switching from firebase.

There are 3 types of objects.

The first two can be both node or leaf.
The third type is a leaf.

I can limit the depth of the tree but would like to keep the ability to add new leafs as big as possible

All of these types of objects are separated into 3 different tables

I've drag/dropped an object ( with many nested objects inside of it ) into my editor and got
4 objects of type 1 and 2 ( nodes with children ) and 13 objects of the third type ( leaf ).

Now a user could easily replicate this complex object and make dozen or hundred of them ( with good or bad intentions )

My problem is that each of these objects are represented by one row in the database and I read postgresql limit was around a billion record per table to still be efficient.

After quick stress test calculations, my number of possible users/database while not reaching this limit of records would be only a couple of thousands.

Is there any workarounds to be able to increase my numbers of users while keeping some easily/quickly updatable objects?

Many thanks in advance