2. But in the other hand some other people, unfortunately, using the money from dad/mom/loan/... Also they want to get the profit in short term.
Those people whouldn't have invested at all. Invest only your own money people or you won't be investing but gambling.
By investing someone else's money you're bringing a third party to the mix. This third party will be able to put pressure on you and disrupt your trading strategies and if you ever lose money that third party will come after you. It will happen even if it's your parent. They will remember your mistake and remind you about it scaring you from making bold moves with your own money.