Thought experiment: You need to upload a file, and the threat model is the entire world trying to find out who you are after you do so.
I know this is absurd, but bear with me, it's a thought experiment, where the scenario is the following:
You are a normal citizen, and you have a file (assume that you just have it, and the file doesn't have metadata or information related to you) that is somehow so compromising/critical that, if uploaded on the internet, the entire world would actively try to find out who you are. Everyone, military, every country's agencies, civilians, the grandma going to the grocery store, yes, her too, to the best of her ability. People who run TOR relays too, everyone.
Your mission is to upload it on the internet without your identity being revealed. How would you go about it?
Update: File is in your pendrive, has a size of few MB, it's ok if it just shows up eventually. No-one should really guess what country you might live in. We can think of the uploader as average-citizen, with average knowledge of technology, and can follow instructions (for example, setting up Tails). Assume that no-one had access to this data before. The thought experiment is not realistic, because one could argue that no upload could be so critical as to motivate the entirety of humanity to find the identity of the uploader, and I would agree with that argument, but the thought experiment is aimed at exploring fairly reasonable routes of action if that was the case.