Two quick notes to counter some of the replies here:

• Google Drive / iCloud backup is an opt-in service -- your recovery seed won't be stored in the cloud unless you choose to store it in the cloud.
• TrustWallet encrypts your recovery seed: it is not stored in plaintext. As long as you choose a long randomly-generated password, your recovery seed is safe even if someone recovers the encrypted version of the seed.

I would argue that storing an encrypted version of a recovery seed to the cloud is far superior to many of the common techniques that people use, such as taking a screenshot, writing the recovery seed in a draft email, or the worst: not recording their recovery seed at all!