Why are they so hell bent on ruining our Constitution and our Country ?
Because that is what they were elected to do? Not necessarily to ruin the country, but certainly to do the things that you think are ruining the country. Remember that the letters we write demanding our elected representatives represent our interests and oppose gun control are being countered by letters from others demanding that their interests be represented by supporting gun control.
There may be a large number of everyday Americans that refuse to be disarmed, but there is also a large number of everyday Americans that want guns to disappear. Congress hears from both sides, and heeds the ones most likely to reelect them.