These assumptions occur because as beginners, they only see the success of traders. But unfortunately, they don't see how traders do it until they are successful. In this case, it very often happens that beginners think trading is an easy way to get rich instantly.
I would say the beginners often see trading as an easy way to become rich because they close their eyes on how a trader deals with losses and misfortune. They think of trading as mostly win-win situation, but winning only never teaches you anything. Losses are necessary to draw conclusions, based on which you could become better and more successful.