Demos are useful but it can never compare to the real thing. You will not react the same when real money is on the line because your human emotions will effect your decision making. People use bots to disable all emotion and they still make very little money or end up with nothing.
It also depends on how greedy you are. Too much greed can lead you into situation where you have to panic sell or panic buy due to FOMO. Strategy matters too. A person who chooses to take a profit of 0.5 to 2% profit per trade will not be emotionally affected like a person who wants to make 50% per trade.
Trust me, emotions are the list of my worries because I don't plan to be greedy.
This demo serves as a test to my strategy, so I am doing it as though I was using real money... because if it fails, then that means my trading plans will have got a hiccup.
I don't believe in bots, they are not my thing anyway.