Personal environment improvement through modelling your inner circle is a rather controversial topic. Many people believe that letting go of your friends is cruel, bad or just unacceptable. Other would say that this way you are only taking advantage of your friends. But there are also people that say your life is a product of your closes friends.
Your inner circle can keep you at your current level forever or it can propel you in space. After all your closest friends listen to your ideas and share their ideas with you. You reach to them for advise and they reach to you with the same. You recommend books to your inner circle and you read the books they recommend. If you are lucky enough you might also be brave enough to start a company together, or they can recommend you to join their companies.