Imo investing and trading are all about psychology and strategy.
Well, that's lack of what it is all about. It also includes finances/money and that's why we want to trade because we either win or lose but mostly, we want to earn and make money out of it.
Intelligence might play a small part but it is not necessary.
That's part of decision making and strategizing so IMO, it's the biggest part and most necessary.
If you are the type who is good at solving problems you will probably produce a good strategy. The psychology part takes time and practice, aswell as life experience
And that includes the intelligence and that means that it contradicts from what you've said. But we do agree about taking time of practice which is common to have experience.