The "bump" button which you can see on the right side of your topic's original post overrides the last's post date so when people use that, they'll end up being on the front page, even if they haven't posted anything for some time.
For additional information, check this thread
Bumping changes on some boards
P.S. From thread title, i thought you're complaining about Bitcoin cryptocurrency which encourage miner to include transaction which have higher transfer fee. You might want to rename your thread title.