This is just a hypothetical scenario. Let's suppose someone saved million of information in blockchain with huge gas consumption so far.
As for reading data in ethereum smart-contract cost no gas. Despite the fact that fetching information from blockchain is not an easy job that's why we have different protocols for that. Is it free to fetch millions of data from the block-chain?
Are there any hidden costs?
I created a scenario and saved 100s of information in an array of struct and it didn't cost a single gas but is it the same for millions of records?