You probably have accounts on different websites or apps where you used your email to sign up. Having access to your email means, the intruder can reset the passwords to gain unauthorized access to your accounts. The result will be far more severe if you keep your debit/credit card added in your account - prompting the intruder to make transactions.
We often use a digital wallet, most of which can be unlocked with your phone number using the simple “Forgot Password” method – facilitating the intruder to empty your wallet. The attacker even may be able to gain access to your bank account.
Moreover, your email may contain sensitive notes, private pictures and have apps you remained logged in.
Use a secure password for your email account. Try to use it only in your personal device.
If you had to log into your email on a public computer, change the passwords as soon as possible.