There are so many ways to get it in a very short time. For example you could find a block explorer with an API that lets you search and fetch hashes with block height then get them from 0 to 730,030.
Or you could download and run a SPV client like Electrum, let it sync for a minute to download the blockchain_headers file which is currently about 55 MB (it also verifies headers) then just read that data file 80 bytes at a time and hash that to get each block hash within seconds.
So basically the time it takes for you to construct such a list should be roughly the same as the time it takes you download 55 MB from the internet.
the tool works in the background, doesn't need any computing power, creates a list for me from 0 - xxxxxx .. so everything is fine... i like to program and that's why i created the tool...
Thanks anyway!!