Say you grew your hair out long and it looks like crap. You didn't take any care of it and just grew it out because you were too lazy to get a haircut. If you were to shave it off and try to grow it back again, only this time to extra care of it, will the results be different? Or will your scalp continue to sprout out not so loving hair? Just a curious question.
Well, if you didn't take care of it then it wasn't your scalp's fault and how you treat the next batch of hair will have a lot to do with the quality of it. Give it a try and see.
Not taking care of your existing hair has nothing to do with the hair under the scalp that hasnt grown yet.
The damage you see in your hair is from the outside. Once hair sprouts beyond the scalp it is dead. That's what makes it damagable. Take care of what's outside the scalp. It's usually the the lower half of hair strands that sustain the worst damage. Peace!!!!!