Hope you can do as well as already existing competitors.

for example altcoinfantasy also is a platform with crypto trading contests. But the most beautiful in that platform it is entirely free to join, But still do offer real prizes by accumulating their AFC points. There also is another trading tournament platform but the name is slipping.

Seen a couple similar projects launch but failed so like many above stated it is very important to not charge to high fees. 10% is extremely high. If you compare with for example the largest online poker room , Pokerstars, deduct such kind of fee, but they already are well established.

I hope you guys really succeed, but you should really reconsider a couple things

fees

In my opinion you can charge a 10% fee but then at least 50 to 75% of the Total fees must flow back to the community by for example launching 'free roll' tournaments but with real prizes, a loyalty program, some kind of jackpot,....

add free games

add some free to enter tournaments where people can win entries in paid tournaments or you can add some of the charged fees back in free tournament prize pools.

Referral

add a referral program. this is one of the most powerful marketing tools. Mouth to mouth. And I think by charging 10% fees you can easily add a referral program.

Multiple winners

As far as I understood only the winner of competition wins the total prize pool. I personally think to make it more attractive you should reward multiple players in a competition. For example if you have 10 players in a 2mBTC contest. Fees deducted gives a prize pool of 0.018BTC. I would reward in this way 50% (0.009BTC) to winner, 30% (0.0054BTC) for second and 20% (0.0036BTC) for third place