Even if you use demo trading account and you make money from it, do not deceive yourself because it is not still about trading with your own money. Trading is about trading with your own money. You can start with demo but use the amount of money that you can afford to lose when you start trading with money.
Demo account is a good way for you to get the feel of trading but it seems that have wrongfully presented it and if I recall correctly, demo accounts have a set amount already and you can just do a reset on your funds if you're doing it wrong, I don't think that it's going to be the right thing to buy demo account money with real money, you're better off just trading straight away if that's going to be the case.
For example, being reckless in demos, as you know you are not going to lose money in demo accounts, you might develop the trait of being too reckless. It can't be done in live trading because one wrong trade might burn all your funds. Treat the demo account like you are trading live.
That's not true, where did you get this conclusion? Also wouldn't this be a smart thing to do when you're on a demo account because you basically got nothing to lose so going crazy to see what would be the result is a valid thing that you can when you're trading using demo accounts. You can certainly treat it like a real trading but what's the harm in doing the reckless, you're going to learn more if you make mistakes intentionally and try to analyze those mistakes.
This is the reason why newbies should not start with demo trading accounts instead they can start with small capital like $50 or 100 or whatever the amount feels nothing to lose that may not bring complete emotions like intense trading decisions but it's a lot better cause it's real money so when you lose you feel that you need to do something about it and that's how we can master the emotion management while doing trading.
And now you're teaching them to lose money when there's an opportunity for them to learn trading without the worry of losing anything besides their time using that demo account. Maybe $50 or $100 means nothing to you but you have to understand that, your value of something that you think is a negligible amount is probably a bit out of touch for some reason.