There are many posts with crypto technical analyses but not many trading contests putting users to the test. Yes you can ask them for screenshots for proof of trades but that's something that can be cheated if the incentive exists to cheat. So how can you create something that can't be cheated? I've been thinking about this for some time so here are some details.
Only do order trading. With a lot of volume coming in now from Samsung news about their partners it will surely lead to the next ones pumping by a picture of big company ceo walking past a shiba inu and seeing dogecoin pump an hour later. I'm not saying let's invest in pump and dump coins, but if this was the bottom then it would not surprise me if it's gonna start happening more often as the world is being introduced to cryptocurrency and blockchains.
With order trading it would work to do this kind of competitions, the only thing I have to figure out is if there would be any legal complications this could bring if you would:
A. Have participants start with "1,000 Steem" on a balance created from air.
B. Users comment with their predictions of any coins on for instance Binance.
C. The trading pool is divided equally among all participants.
D. When new participants want to enter, the pool is divided equally and new user gets the same amount percentually as the first users that joined had, minus current profit.
E. Users can only edit their order or adjust part of it into another order once per day.
F. Each week users are checked for P/L according to their predictions and receive an update of the control of stake they are trading with depending on their performance. (more frequently if we go as far as to automate the calculations and scanning)
G. Once a certain momentum is gained and (if) profit is made gradually over many weeks, we start withdrawing a percentage per week out of the profits and into an account that delegates to 
H. When the returns start coming in from ocdb
I. Extra trading pool from posts going 100% beneficiary to an account that sends them to the exchange. the majority is shared among the participants and the "house" takes a cut for the effort of doing these posts and the trades.
So point G is of course the problem, not which "bot" I am using to make rewards, but sending people "dividends" if the numbers start getting high in $. I understand that each country has different rules for "sending people donations" and limitations until taxes are involved which could complicate this. I am not so sure about this part so I would appreciate if someone in the comments knows better!
The good thing is that participants never have to invest anything except their predictions and time yet they could make most of the decisions and withdraw free steem whenever they want from the returns and profit. I'm guessing it might depend on my location as the one trading and sending out the Steem.
Anyway, if anything this idea could show some cool "wisdom of the crowd" in action, combined with a requirement of having posted about crypto and trading in the past to enter it could be kinda cool and users could use that number to flex on other traders while getting some rewards from nothing. It would also add some more volume to Steem in one go. :D
Thoughts about the idea? I have a lot more ideas about the dapp that could make it a lot of fun, if someone wants to steal the idea then feel free to. There are probably a lot of ways you can automate a lot of this stuff with API's etc and giving users access to their share of the funds trade without being logged in on those exchange accounts to begin with. Add some Steem incentives and you're good to go to create something cool that may even work. :)