Maybe in theory it is safe, but implementations are often not safe.
An oversimplified way to see this is that your software runs on an OS which runs on a processor.
Your processor is backdoored (Intel ME and equivalent), your OS is backdoored, the entropy for your crypto is backdoored (Intel RDRAND instruction), your crypto algorithm implementation is backdoored.
So there are infinite resources for them to hack you at any moment for any reason. You have already gave them the keys to everything.
Maybe in theory it is safe, but implementations are often not safe.
An oversimplified way to see this is that your software runs on an OS which runs on a processor.
Your processor is backdoored (Intel ME and equivalent), your OS is backdoored, the entropy for your crypto is backdoored (Intel RDRAND instruction), your crypto algorithm implementation is backdoored.
So there are infinite resources for them to hack you at any moment for any reason. You have already gave them the keys to everything.