Well, it is not harmful to sit closer to the TV. It will not damage your eyes, but it will strain your eyes. Your eyes will feel the strain quickly. If you do this for a few years. Your eyesight will be strong at the shorter distance but weak for longer distance seeing. It is recommended to follow the viewing distance formula above for this. But still, take breaks after year 2 hours and go out. Don't binge-watch for the whole day straight in a row.