I have now been doing startups for nearly 10 years and have met up with founders all over the world in a dozen countries. The ones who have some degree of success seem to have these 6 traits:

• Relentlessly resourceful
• Intellectually honest
• Infinitely curious
• Emotionally stable
• Quick to respond and act
• Highly Empathetic

Relentlessly resourceful

This phrase comes from Y Combinator. The driven ability to continually be productive over a long period of time in the face of numerous obstacles. This includes both personal ones such as a close family member dying as well as professional ones like getting legally screwed over.

Intellectually honest

Knowing where you and the company stand in an honest way.

The cares about the success of the company first and foremost. More than their own ego.

Knowing how to price things and anticipate customer needs realistically.

Infinitely curious

Being open to in depth discussions on a wide variety of topics. This is important for listening to customers and being creative with how the product can evolve to suit the needs of a changing industry. The biggest company founders I know completely turned their company when the opportunity rose fast and confidently enough to take advantage. For instance, I turned my own logistics company from 5 figures into 8 figures by shifting away from our consumer amazon reselling product into our own branded products such as PPE early enough during the covid pandemic.

Emotionally stable

Not getting hung up on whatever emotions are being felt that day.

They can disagree with their cofounder and debate comes to a conclusion in a mature way.

More generally, they are happy people. They do not get angry on a daily basis.

Quick to respond and act

Responding to emails and texts within 24 hours. This is how you win customers by showing you care. This is how you have better customer support than the competition.

Also, no procrastinating. Getting shit done when they say they will.

Highly Empathetic

You want to be empathetic to customers and coworkers. You need to care about what their problems are.

Understanding the social contract. Anyone who interrupts others or rudely wanders away when someone is in a conversation with them. Knowing how to get out social situations without making them awkward.

Put another way

In a psychology context they say high achievement (and coincidentally a good romantic partner) is closely linked to high consciousness, low neuroticism, and medium to low adventure seeking.

I would say startup founders have a peculiar, somewhat contradictory type of adventure and agreeableness. You want to be empathetic to customers and coworkers but relentless in progress. You want the willing to have high ambition but also enough to stick to a single thing for years.