Yes, you can lose your password for a cloud service or leave your mobile phone in the back of a taxi. But the most likely way for you to lose data is still when a hard drive dies.
Hard drive picture from Shutterstock
A global survey by data recovery company Kroll Ontrack highlighted that hard drive crashes and hardware failures remain the most common source of data loss. The infographic below sums up the numbers:
The lesson is simple and familiar: any data stored in just one place is going to be lost sooner or later. Backup, test your backups, repeat.