Why did the mad king kill the Starks?

Related questions

1. Is the waif Arya Stark?
2. How old is Arya Stark now?
3. How old are the stark siblings in Season 1?
4. Is jaqen a Ghar syrio?
5. Could Tyrion be a Targaryen?
6. How old is Sansa Stark now?
7. Can Jon Snow and Daenerys marry?
8. How old is Jon Snow in the show?
9. Who created the night king?
10. Who was rhaegar Targaryen married to before lyanna?

Tags

1. #executes
2. #starks
3. #freed
4. #father
5. #targaryen
6. #lyanna
7. #older
8. #scatter
9. #robert
10. #brandon
11. #prince
12. #trident
13. #aerys
14. #decisive
15. #rickard
16. #convinced
17. #demand
18. #battle
19. #called
20. #usurp
21. #brother
22. #manages
23. #rhaegar