Answer:
No, he should not pick up the $100 bill
Step-by-step explanation:
If his salary were those $20 billion (20,000,000,000) by a year. Let's find out how much this is by a second.
First let's find out how much is that salary by a day, then by an hour, then by a minute and finally by a second.

So he would be losing money if he picks up the $100 bill, because he would be missing 634 dollars per second.