To clarify the math:

Add your name to the top, take the 5th name off the bottom.

Each forwards to 5 people and with the same instructions

Would end up:

5

5x5

5x25

5x125

5x625

= Potential 3,905,000

Now, in reality, the same people would likely get spammed the same message and the we'd track down who the asshole is that started this mess and insta block.