I would find a worker on steem, who got a concept to write post every day. Create a short contract with him, then invest the money to buy steem coins, to power up his steempower. Then the 10k would affect the price up steem, and it will rise. Second, the agreement what i would make is, he needs to power down and give 75% of the power down ammount. And he needs to pay the full 10k back with the power down. Second, he needs to give 50% of every reward he makes to me, until he paid the full 10k back with the power down, and then he is free. Third, he needs to automatic vote 10 shrimps, to boost others with his high vote. Now this could work if the worker got a concept to create 3 or 4 post every day. And with the 10k boost on steempower, it will lead to more votes, higher reputation and he can easily earn more than he will lose with powerdown. What leads to a daily and weekly income, higher steem price and the worker get a boost with his account, and he can boost others on the same time. And within 13 weeks you got the 10k back, if price don't change. And the profit will be in the daily rewards. But this can only work with someone who you know personal, or you have to make a good agreement with someone, like a legal contract. And if you ask me, there should be a application made on steemit, what can create contracts between members for cases like this. Delegation with a small twist. :)
So if i had 10k to invest, then i would invest in myself and do everything what i write above here.