Well less expenses, more money to spend on other more worthwhile things. So yes, you can say not buying is "earning" if you actually put the saved money on something that gain value.
I don't agree so much about refusing to "third-party" tasks. As you progress you'd want to be able to delegate/outsource many tasks to leave you with more time to then use to other more important actions. Time is something worth paying for.
It all matters about management of things on which it would really be just sensible act for you to do so on dealing with something which you can see for it to be useful in longer runs rather than on dealing up with something specially with expenses and not worth kind of spending which would really be putting you out on a big trouble once emergencies and needed of funds would really be happening.
Speaking about getting different various sources whether from other work or some investment or business then it is really just a casual thing or mindset of everybody.
Doesnt matter on what form and what way as long it could give out the chance for you to earn more then thats what it counts.
Well yes, if you can earn more by delegating a task, then that's a good reason to do it. If someone can do it better than you and you can pay that person something less than what you value your time, then good.