Another differential is one investor knowing what they are doing and some having no clue.
Is that relevant to the article posted which was about oil price differentials not investor abilities.
You did miss out another type of investor, the type who are convinced they know what they are doing but don't. They are the worst type. They tend to shout about their abilities and convince others to follow their lead. Their followers make money in a rising market and lose their shirts in falling one.
Beware false prophets is wise advice.