[grumps]

Essentially this is how some web/digital agencies work. They higher people and contract out the work. I see nothing wrong with it ethical.

That just depends on your ability to market yourself. In reality I would suspect you'll just evolve into hiring people to reduce risks associated with freelancers.

I assume you have some legal contract that you put in place with your clients. I would ensure that it says you can subcontract out work.