If you bet on these things against the house you'll generally have to incur a lot of fees and charges and it's just not worth it.
You can leverage up to 100x on most exchanges, which is essentially gambling.
Turning the question around: Is it actually possible on betting websites to bet on where the Dow Jones or S&P500 is at a certain time? (Similar "problem" applies here, but for large stock indices an easier solution might have been found already)