It's very easy not to be around. I was in the same place you were, all it takes is not hanging out with them. If you continue to, I can guarantee your chances will be detrimentally affected. It shows a lack of willingness to accomadate your life to get into the profession you want to get into.
These type of friends will never support you going into this field, anyways, so find a group of people that are mature and preferably law abiding.
Astronomical avatar of the week: The Hourglass Nebula: This formation of gasses was created when a dying star gently ejected its outer layers forming a glowing region of ionized gas as seen in the photo. The remaining core is known as a white dwarf, seen in the center. Our sun will leave a similar corpse behind after expending its nuclear fuel. This nebula is located in the constellation Musca, the fly, visible only in the southern hemisphere.