None! they exist to promote a brokerage or other service. Also, no one cares if you win one, as 9 of your ten accounts in the contest could blow up. The only way to win a contest is to take ridiculous risks.
Anyone promoting services claiming to have won a trading contest is basically saying "I cannot do this in real life, but I returned 10,000% in one of ten accounts".
They would use real returns otherwise.
If you want to eventually run a hedge fund, etc., get your real returns audited. You need to set this up before a period in which you trade, not after the fact. No one knows how many accounts you had otherwise.
