The freelancer who take your outsourced work, bring in years of experience and expertise with them. If you want the best talent to do your work exceptionally well, you must outsource it to external freelancers. Other way is hire a permanent employee with same experience and skillset, this will cost you much higher even when there is no work. So when you need extraordinary expertise, outsource your work.
Right degree of risk is a must in a successful business. But there is no fixed standard to measure the amount of risk you are going to take. Chances are you might think some certain risks are takeable for you when actually they are not. It lets you to take the risks that come under the tag of foolishness. So why not get a help of someone who already has gone through same risks 100 times. Outsource your work to him and maximize the profit by minimizing the risk.
First challenge in establishing a successful startup is hiring really best team. Which is a very long and time taking process and needless to mention ongoing hurdles of managing a team. Freelancers on the other hand are more understanding in this aspect they expect their billable hours to vary time to time.
Lets be honest, what is the biggest challenge in establishing a startup? Getting funds. In initial days it is hard to get required funds and hence to sustain your business. You would want to save the maximum money you can. Freelance marketplaces are very competent with unlimited number of talented freelancers, you will always get the best possible talent in your budget.