The key quote from Pew Research's Self-employed people in the U.S. are more likely than other workers to be highly satisfied with their jobs is:
"Most self-employed workers (62%) say they are extremely or very satisfied with their job, compared with 51% of those who are not self-employed. They also express higher levels of enjoyment and fulfillment with their job."
As the Pew Chart below shows (click to enlarge), the self-employed also are more likely to find their job more enjoyable and fulfilling than other workers.
Regular readers know that almost all studies on the self-employed have found similar results.
But it's nice to get confirmation from Pew Research - they're considered one of the world's top research think tanks.