
It depends upon what you mean by a 'pyramid scheme'. But, no! Pyramid schemes are illegal and are characterised by not having a real product or service to sell. Network marketing (aka multi-level marketing) is employed by many leading NYSE & FTSE firms alongside, or in some cases replacing, more conventional sales channels.
All of the easy ways are illegal I'm afraid..
Easiest way to make a small fortune is (allegedly!) to start with a large one and go into Motorsport...