Not a diehard fan or heavy user of it anymore but it is, frankly, weird you'd even need to ask.

• It's available where ever you have a connection. You can't forget it or not realize you would need it. It's just always available.
• It's off site if something happens at home.
• Assuming you trust them, your data is safe. It's not going to fail. It's managed by someone paid to keep data safe for you. Economies of scale let them have more redundancy and verification than you. No stray atomic partical is going to flip a bit while it is on their servers.
• You can be lazy about it. I keep a working NAS, an older, slower NAS I back up that NAS to, and gave family offsite another NAS that I also back up to. I have many backup tasks and don't rely on cloud storage. However, I need to, at least on occasion, make sure everything is still working... or I can fuck something up if I don't property document or pay attention when doing anything major. Wouldn't need to worry about that if I just used the cloud.