What is wrong is when people expect too much from deposit bonus or when people think that they are on +EV by taking deposit bonus.
Yeah, most of the time when the marketing of the casino is too good, as someone who was attracted by the numbers given, they just eventually deposit or register to get the deposit bonus without knowing they need to achieve a pile of requirements for them to be qualified then just to get disappointed and feel cheated once they contact the support or reread the bonus terms lol.