Ancient egyptians

This is me as a egyptian person.
The photo is from Face in the hole.

I know:
I know that the heart was weighed against a pure ostrich feather. If the heart was heavier than the feather Ammit, a crocodile, lion, hippo, would eat the heart and the person would not go to the afterlife.

I know that when people were mummified they were put into tombs with their riches and had a heart amulet to protect their heart.

I wonder:
I wonder why people were mummified instead of buried, why were people people put in tombs with their riches.

I wonder why people spent lots of riches on making their tombs really nice. Was it a tradition or did it make them respected.

Thank you for reading this.