using wordpress to provide websites/webhosting

Hi, wanted to start a wordpress hosting service for a fee like tumbler or squarespace. i have just noticed that i might have underestimated what needs to be done. thought pro site is all it took.

Would appreciate if you could guide me as to the things that are required to run such a service.

PS: my target customers just need a simple website that they can design with ease but has to look good