It is not the financial markets, nor government intervention in the markets, nor even the other competing traders that are the greatest enemy of any speculator, it is the greed and fear dwelling deep within his own human heart.  To become an elite speculator, one must carefully learn over decades of real-world trading how to turn off one’s own dangerous emotions of greed and fear like a switch.  The goal is to be totally emotionally neutral, never growing too scared nor stumbling into the deadly trap of greed.
A greedy speculator is doomed before he even starts because he will buy in at the wrong time and will inevitably fail to sell high when everyone else is confirming his greed and bidding up prices.  A fearful speculator will fare no better, as he will be too scared to buy in at the right time when everyone else is also frightened and he will sell out too soon as his fear multiplies, missing most of the market move.
Jesse Livermore learned through long, hard experience that his own internal greed and fear were his greatest enemies as a speculator.  Once he learned how to tame his own dangerous emotions when he traded, both his success and fortunes soared.