Lightning network scaling (Reddit Bitcoin)

I sometimes read concerns about LN scaling, and how it scales “quadratically”, meaning it cannot actually scale according to it.

From what I’ve gathered there would be around 100k LN users currently. (not 100% sure)

How would LN react, in terms of fees, bandwidth used, disk space used, if that number went to 1 billion users? (a 10000x increase)

And how to determine, as of now, the bandwidth , disk space required, for using LN is a self sovereign way. Having a dashboard estimating the users would be very useful too.

Thank you