I have recently applied for enlistment in the Air Force and have qualified for all the top tear jobs, most of which require a TS clearance. To my chagrin, as a teen I immersed myself in youth party culture and from the time I was 18 to 22yrs old, I lived as a degenerate where I made my living by selling narcotics. During this period I was well acquainted with cocaine, amphetamines, and hallucinogens, but was fortunate enough to avoid any confrontations with the law. Apart from a few traffic infractions, my criminal record is clean.
I have abstained from these substances since 2012 and have since done much to change the course of my life. The person I am today bears no relation to the one I was then and along with a great credit record, I have many references, both personal and professional, that will attest to my character.
My medical record is also sound, containing no record of drug abuse, clinical depression, or any other mental or physical health condition.
I fear that if I omit my personal history on the SF-86 it will come back on me negatively and so my question is, have I a prayer of being granted TS clearance given my past behavior?
You are considering leaving out your history with illegal drugs? That would create a brand new issue called dishonesty and lack of candor which would be hard to overcome. The drug involvement itself can be overcome (look at mitigation under the Adjudicative Desk Reference). Be up front about it as it is always easier to remember the truth on future applications and polygraphs rather then trying to remember a lie.
Producing a false SF86 is simply a continuation of the behavior that you are concerned about reporting. The reality is that the truth will come out sooner or later. It’s far better to be in front of it instead of in the rear.
Apply . . . The advice that you have been given is based on the statement, "I fear that if I omit . . . " which is tied to your question about having a chance of getting your TS.
If you omit it, it will come back on you negatively. You certainly have a chance at gaining a clearance. It will, of course, be made more difficult by your past but you should, if you are willing and able to be completely open, be able to accomplish your goals.