Yes he could have made that much... if he bought 800 shares, paid no trade fees, and didn't include capital gains tax.
And yes, it is that easy. However, that stock could have just as easily gone down by that same amount, and then he would have lost $1,200. Looking back and saying what you "should have done" is extremely easy... hindsight is 20/20. There's even a term in psychology describing how people can look back and think they knew something all along.
Truth be told, the stock market is a guessing game unless you really devote your time to some in-depth research and/or really expensive valuation software. Your friend COULD have made a quick $1,200... just like I COULD have won the lottery last night if I knew what numbers were going to get picked.