Ask yourself these questions:
1. What is the motive of a company that mines for you? If they build, deploy, host, colocate, maintain, and consult you for a fee, why wouldn't they just mine for themselves if they already know how to do everything? What is the reason for you to exist in this scenario?
2. If you realize that the only reason for you to exist, is because you have money, and they don't, congratulations, you are on "step 1". If they are an established business, why don't they take a business loan at 6% interest from a real bank instead of paying your "share" of the profit of up to 50%/month?
3. If you realize that the only reason for them to take your money is because they are shady or scammy, congratulations, you are on "step 2". So, why would you risk giving them any money?
4. If you realize the only reason for you to give them money is because you are a certain combination of lazy, stupid, and greedy, congratulations, you finally arrived at "step 3". Now you can finally begin to learn how to mine yourself with the resources commonly available online.
You are right. If you can rent the rigs directly through Nicehash, you will have to pay the market rate, there is not much profit to make.
No, doing that is a bit stupid, because you could buy the coins directly, it will be quicker and easier ...