Let me refer you again to what GPT said.
Well, I was curious so I downloaded TraderView to do a like for like.
I opened Chrome, added 7 random tabs.
I ran TraderView.
I thought I'll open Safari as well and opened 3 tabs.
Then I thought I'd open a spreadsheet in Numbers just for the hell of it.
I flicked through them all quickly opening each tab one after the other and randomly selecting the apps as I went.
Long story short, when I first opened Chrome without adding a tab, the Memory Used barely changed to the screenshot you see here.
So for you to say...
It's simple Math. If it can't hold 8GB on my Mac how will it hold 8GB on an Air?
..., is not so simple maths at all.
For a start, you've got a 16GB machine so where does it say your Mac can't hold 8GB? As
@backstreetboy said, you have the memory sitting doing nothing so the machine is going to use it. And when you have less RAM as I do, the machine copes very well because, well, it's absolutely not "simple math".