I'm too poor to be angel investor but I do like to listen angel investors and venture capitalists because they can give me insights about how to find brilliant ideas and what's common signs of prospective ideas.
I think advices from ex-entrepreneurs who turned into angel investors or venture capitalists are much more valuable than from first or one time successful entrepreneurs because they know both sides. It's hard to impossible to distinguish talent from luck based on one time success. But if someone repeatedly find unicorns over the years, it's most probably talent and I would listen that person with great attention.
One of my key takeaways from these lectures - really good idea for startup often sounds like bad idea because if idea sounded obviously good it would be most probably already executed by some big corp.
This takeaway teach me not be overly dismissive of ideas which are not obviously good and be careful with ideas which sound obviously good.
P.S. I know that soft-skills (e.g. leadership) and team are very important for success but it's not insightful information.