Traders League is much more than just a leaderboard, it's a place to practice your craft, gain real market experience and develop as a trader. Whether you are participating in short-term events or developing a long-term consistent style, it forces you to stay constant and be more disciplined. For example, I've found my involvement in a league forces me to not trade on emotion, and to focus on my specific plan - despite significant volatility and drawdowns in the market.
Not all leagues are worth your time, though. Some are just polaroid competitions that reward the "luck of the draw", despite your skill as a trader. Before you get involved in a league, check the rules to understand fully the risk to your capital, and try not to let the leaderboard or other traders lead you to reckless trades or risky behavior.
For me, the value of Traders League are how I can improve from where I am, not necessarily just how I can increase my account balance. It is an accountability mechanism, it forces me to build a position and allows me to see how different things can work - or not work - under stress.
Stay competitive, but stay sensible. Your goal should be long-term development and growth, not short-term accolades. And as always, do your own research (DYOR)!