The problem with time travel is that when a single person can do it than we can all do it. And none of us will get ahead. Every time a startup tries to predict

The problem with time travel is that when a single person can do it than we can all do it. And none of us will get ahead. Every time a startup tries to predict the stock market, they are investing in a time travel startup. And that's why they say the market is efficient - no one can predict when the next crash will come.