Your password leaks somehow, somewhere: Most intelligence agencies in the world have access to your wallet.
If you use LiveCD Linux, it is almost impossible. Can happen only if you are person of interest for them and they have installed hardware keylogger or other spying device into your PC.
Encryption is not that rarely broken and cloud services have a lot of computing power. Although risk isn't super high. it is still not negligible in my opinion.
I don't think it is easy even for NSA to crack 30 character password for VeraCrypt container with AES-Twofish-Serpent cascade encryption.