Chasing people around in life will be of no benefit to you in the long run. This is mostly because you can't make people be who you want them to be, people will always do what they truly want to do, deep down inside. What you can do is make extraordinary effort each day to be you, and to do what is in your heart, and work hard at it.
The people who deserve to be in your life will come in your life, and not only will they just be a part of your life like the people of your past, but they will stay in your life as well. Cut the slack out of your life, and let go of the people that are only bringing you down. There is no reason to be burdened continually by people who don't believe in you, when there are people out there that will.