People like me don't move the market, but Ackman with a $billion one time bet on Netflix do. The stock is up more than 8% today, which translates to Ackman making more than $80 million dollars on his bet, and the day is young!
If you follow your own advice, then you are a participant, even if just a small one perhaps. Buy your involvement encourages others to follow. Not you of you personally investing, but early rises after a big-hitter invests is a positive sign for others who fear they will miss the boat if they fail to act quickly to maximize their potential sure thing gains.