It seems the average Big Mac meal is $6 these days. It provides approximately 1,000 calories, and the average person needs approximately 2,000 per day, so we'll assume you'll need to order two. That puts the food costs at $12 per person.
The average cost to install a kitchen is around $60,000. If we assume a rate of return of 5%, that is $3,000 per year right there that the money needs to provide to justify it being invested in a kitchen and not invested elsewhere. That covers more than half of the individual restaurant cost right there and leaves only about $4 for everything else. Does $4 even begin to cover the time it would take you to make your own Big Mac meal (I agree that it isn't fair to compare with lobster) at home once, let alone twice? While the average home has 2.5 people, not just one person, we've only just scratched the cost of having a kitchen. We still have ingredients to pay for, the opportunity cost of occupying the land, electricity/gas, taxes, repairs and maintenance, etc. You're blowing your $30 budget in pretty short order. Okay, if you are one of those TV families with 14 kids, then perhaps you can gain some economies of scale at home.
Yes, if you've already invested heavily in having your own kitchen, then you can become more price competitive with a professional kitchen. Though that is true of a lot of things. After you've invested heavily in having your own silicon fab, you're going to laugh at how much Intel is charging for their chips as well. The means of production comes with a cost, though. And while it may be a sunk cost for most, it should not be ignored on that basis.
The real world is complicated, though.
1. If you're buying a used home, as most people do, they rarely come with silicon fabs but virtually always come with a kitchen, leaving you little choice in whether or not you want to invest in one. If land is cheap, it usually doesn't make sense to divest yourself from owning a kitchen. However, if land is expensive, then the calculus changes. When land is expensive, the land occupied by a kitchen can be put to more productive use that outweighs the investment you have already made.
2. Because most people are invested in home kitchens already, restaurants aren't optimized for providing food you want to eat on a regular basis. Eating a Big Mac twice a day, every day isn't sustainable. But at the other end, non-fast food restaurants focus on providing entertainment. Your kitchen can compete with them as your kitchen doesn't have to be entertaining. To be fair with them, we would have to include the cost of having a living room, TV, Netflix account, etc.