-cut-
Besides your example for sports betting as demo is really not necessary. No one wants a trial bet to experience sports betting because the sports game will play with or without your bets and you can experience it by just watching it and make an assumption bet compared to casino games that you need to play for the result. This is my first time to here a demo on sportsbook.
No one? I just literally said that i would like it. Or at least it would be a nice option to have. Just because it wouldn't fit on your taste doesn't mean i would somehow change my mind because of it.
Because sure, i can bet winners and results, but i have no experience using anything else then straight forward betting so i have no idea what for example handicaps or totals mean in the choices. So demo money would give me ton of confidence to execute my bets later irl as i could have tried them out. Also i could test out new tactics in betting to get a better feeling for it.