Their last round B is $20M. Say if VC has 3x preference and also participation.
B round VC will take $60M out of $210M.
A round and angels will probably take out $25M ($8.5M x 3)
And then they will share with everyone else in the remaining $65M.
So your friend with $100K joining after B is about 0.0014%. He will make 0.0014% * $65M = 91K.
Yes he actually takes home less than 100K in this scenario.
You really need a 10X exit to have some meaningful outcome, sadly.
Alternatively you need to get a very good VC terms to have smaller liquidation preferences.
If it’s 2X liquidation preference, then he will make about $214K.
So it varies from case to case.