To be frank, that's not the only question. Another question is: do you have experience as a marketer? Yet another: do you have experience in crowdfunding? If the answer to both of those is "no", you should consider hiring an agency. There are certainly ways to go without hiring one (for example, if you have an awesome course and coaches to help you!) but at the very least it is good to understand the nuances of both options.
One of the best parts about hiring an agency is that you can still stay in the driver seat for much of the marketing, but you let the professionals deal with the details. Depending on what services you are getting from your agency (content writing, ad buying, events, media placement. etc) you should insist on a marketing plan for each service. This will allow you to understand what is happening, when it is happening, and how your money is being used. Most good agencies will provide ideas for your campaigns based on competitors or other successful crowdfunding offerings.
I'll never forget the first week of PopCom's paid ads during our first crowdfunding campaign. We spent months and months prepping, writing content, making the StartEngine page perfect, and creating 15 second videos to get people's attention on Facebook and Instagram. The ads worked beautifully for a day, and then stopped by their review team. Facebook had decided our ads were against their content rules because the offering mentioned both blockchain and cannabis. Even though we were selling neither cryptocurrency or cannabis, we still were unable to advertise. If you've ever had to deal with Facebook support, you know exactly what the process is: attempt to argue with them, get a copy-and-pasted response, and rage as nothing changes.