Why is it hard to create success on consumer based products?

It seems easy & quick to get an idea on the consumer facing web products, but it is tough to monetize & make it successful, below are some of my thoughts:

1. How do you attract the user to your site & retain them?
2. Create repeat visitors & keep them on your site?
3. Generate page views in 100s of thousands or millions
4. Invite user to join the network, away from their current networks?
5. Ability to have unique value proposition to the product is a challenge

-Bhaskara