There are many reasons why a project dies and it may happen commonly to new projects or shit projects or projects that don't have strong fundamentals.  Commonly they are:
- Projects with no fundamentals
- Projects with the hype created following only
- Shit projects
- Projects with the non-professional team so that they do not know how to develop the project
- Projects that only focus on crowdfunding or selling their token and will disappear after it
- Projects that do not make good development and progress especially in listing exchanges
- Projects with no real use
-project with very low trading volume and market cap

And about the top 10-20 coins, I think they have their strong reasons and fundamentals why they are at the top 10-20. So their chance to survive is higher.