It depends on the forum and its activity. I usually hire a team in order to support me and help me. When you begin your forum, you don't have to hire staff. If your forum has many members and many topics/posts then, you need to hire staff members.
I haven't really run a forum before, but I have helped my friend creating one. We teamed up with 2 more people, but the site ended up being inactive except for some members that show up here and there.
On most ventures, I prefer to work on my own. However, sometimes websites or, in this case, forums become too large for a single webmaster to adequately do regular check ups, clean ups, and moderation duties. At some point, depending on the popularity of the forum, how much users post, and the frequency of spammers or rule breakers that visit the forum, a webmaster will find it in his or her best interest to either ask a few friends to join their team of admins, or confront loyal users of the site with an offer to help out.
Then, there is the issue of compensation. Will they volunteer, or will they want to be paid for spending time cleaning up and moderating? If the forum does really well, I wouldn't mind paying for staff, but if it's for hobby or you aren't doing so well financially on it, settle for a team of volunteers. It's better than nothing.
It all depends really. When I had my site which is a giant, I work on it by myself as an admin. and had the community posts for me. They could post anything that they wanted and I just have to moderate. I do all the moderating there. I make it go through an approval process so that they don't post junk on my site but there were lots of spammers. If your site has a way where you can manage it easily, you don't have to hire many staff unless its like Facebook. If its just a blog, you can handle everything yourself until it grows to like more than two hundred thousands users then its time to hire your family to help you out. Why not? Your family will not sue you and will work for nothing. You can hire your friends or girlfriends.
I only get staff that i trust. Basically i only accept staff i know for some time (i am not talking about long time friends, but someone i know that will suffer as much as me for the sake of the project).
I would rather choose a team. I want people I trust only to be admins and have ban privileges, mostly people I know or talk to frequently. Dedicated members can be mods where they can ban or delete threads if there is spam around on the forum that the admins, or I didn't catch.
Talking about management of forums or websites...? Really your traffic and the content in discussion will matter a lot… you do not just launch a new forum today and hire as much staff... definitely this will cause a prompt close up due to insufficient funds.. But if you have a giant forum with a strong foundation it will be a good idea you hire staff to assist you but at your own risks. You need to hire reputable people not anyone else you find on the streets eager for the job.
I would certainly start it off all by myself, since it really doesn't take that much work to install a forum and get it set up. Plus I know how to do all the graphical work and customization via HTML and CSS, so I don't need anyone else doing that for me. I also work in Internet Marketing so I have that covered too. I wouldn't want to bring others in unless I could perhaps compensate them for their work.