Harder does not mean better. Cleaning your teeth all comes down to good technique.
When you brush your teeth too hard, you can cause damage to your teeth and gums.
Over time, your gums will start to shrink and your teeth will become more sensitive. Angle the bristles on your toothbrush head towards your gum and clean each and every surface, of each and every tooth.
Don't make your toothbrush become like this!