There's a difference between investing and speculating. I am a marketing professional and my wife is a nurse. We do not keep credit card debt and the debt we have is good debt. We put about 800 a month in savings. Having an emergency fund, especially for young people, is crucial.
People change jobs seven times in their lifetime.
Always expect the unexpected, so having 2-3 months of living expenses in a liquid or readily accessible investment is a really good idea. It could be as simple as a money market account. For a short term horizon, a CD or money market account are excellent tools. If you know you'll need it, keep it in cash. The stock market's simply not insured.