hello a friend recently told me that bridging your network damages is by causing your wireless network card to dull down in connectivity with each time u use it. is this true? and is there any harm done to the card by bridging your network?

Nope your friend is wrong or you mis-understood them. No damage is done but there is an adaptive feature of wireless network equipment that can vary signal strength based on environmental conditions.

usually these adaptive changes are temporary and don't have any long lasting effects.