I'm not against making money in any way, but $400 doesn't really seem worth the effort and coffee expense invested (I like the good stuff). This is a very basic example used to put the costs in perspective. Most SEO providers charge more than $50 per hour, and you get what you pay for. The above example of a final labor estimate is probably much higher, or if the domain is already ranking high and the owner wants to sell, so is the initial purchase price. Since this is often repeated many times over for multiple domains, it could get time consuming, and expensive.
The domain name industry is quite similar to the real estate industry in a lot of aspects. There are end users, brokers, consultants and domain flippers or “domainers”. Domain flipping works similarly to buying a house, renovating it (or even sometimes just sitting on it) and then selling it again at a higher price point. The gist of it is: you’re purchasing a domain name and betting it’s worth (or will be worth) more than you paid for it. If you’re right, you get a nice paycheck and move on. Those who make a living out of this just rinse, repeat, and scale.