> In school we were strictly taught the market is efficient and I fully believed that. But I've seen online and discussed in person a (seemingly) growing idea that markets are not in fact efficient at all.

I can tell pretty much everything I need to know about a person based on which one of these ideas they would say or defend.

Always lots of new ideas and theories that hope to reduce the participants in a market down to an explainable behavior.

But there are lots of ways to extract value from a market, which is more important than the debate around "already 'efficient' or not".