You need a recovery plan for the data you care about.
Redundancy is not sufficient.
The value of raid-1 and it's variants like raid-5 is that you can recover from a drive failure quickly. It is for servers that can not tolerate any interruption.
Modern hard drives have a advertised mean time to failure on the order of 500,000+ hours. That is something like 50 years. SSD's are similar.
With raid-1 you are protecting yourself from specifically a hard drive failure. Not from other failures such as viruses, operator error,
malware, fire, theft, etc.
For that, you need external backup. If you have external backup, and can tolerate some recovery time, you do not need raid-1
1) RAID for failures
2) Backup of the things you are protecting. There are a lot of different backup strategies that depend on your specific requirements; you can consider web or online storage too for the real crucial data.
Some people have requirement to protect against a situation where their physical location will be gone (like a fire, natural disaster, terrorist attack etc explosion, etc). That requires a more robust solution; but maybe the same things to consider as a home user. Your house may burn down too..