Don't get a growth stock confused with a mature stock. I'm not...

Don't get a growth stock confused with a mature stock. I'm not sure where you are getting this blanket rule of "500m-1bill" from to justify this statement, but this doesn't apply to a growth stock.

To explain with a simplified example, would you rather pay $40 for a company making $1 billion right now or pay $40 for a company that's making $0 because they are heavily expanding but could be making $10 billion in 10 years time?

This question isn't meant to be accurate or answered as it is just there to demonstrate that there are different investors buying companies for different reasons. Investors who need to see profit and collect a divvie won't be looking to pay $40 for Afterpay, they would likely be looking at the banks and miners.