Ask HN: Can someone run a web agency on his own?

I'm a fullstack web developer, and have been freelancing for a few years now. I've learned a lot in that time and think that the next logical step for me to boost my income is to start a web agency. I like to consider myself a one man team, i'm good at development, design, marketing and SEO. The thing is, i've never worked at an agency so i have no idea how hard it could be. I have a lot of plans to get clients and increase the recognition of the agency once i start it, and will be hiring people down the road. I'm just wandering if i'll be able to survive that long.