Ask HN: Have you created an online course? If yes, how was your experience?

I'm a software engineer who is passionate about online education. I'm thinking to create my first ever online course on technical interviews.

I'd love to learn from your experience if you ever created an online course (MOOC):

1. How much time did it take you to create the course?

2. How much did you earn? Can you share any numbers?

3. Lessons learned.

Thanks.