What's great is because your "free" 5GB are tied to your Apple ID and not to the number of iOS devices you bought, the more you buy iOS devices the more you need to buy iCloud storage.5 GB serves the needs of many customers.
If you need more, you can purchase 50 GB for $0.99/ mo (3.3 cents/day), 200 GB for $2.99/mo (10 cents/day), or 1 TB for $9.99 (50 cents/day).
Simply pay for what you need.