Yes, if you cherish them. Your data can be corrupted in the event of a ransomware attack or human error.
Office 365 is vulnerable to both ransomware attacks and data loss due to human error or malintent. None of Office 365 services is safe from these events. Furthermore, Microsoft has limitations to the file recovery time. There’s a great chance you’ll detect the data loss after the recovery opportunity expires. Why backup Outlook/ Microsoft
Data loss damages business operations and business continuity. It can result in financial and reputational losses. The laws in most countries stipulate mandatory backups for data.