Of course the manufacturing cost is considerably smaller for restaurants, but they charge a significant markup, which is the only reason eating at home costs less. It's funny that you mentioned McDonald's, I shamelessly love it (in moderation, of course), but in my country it's not the dirt cheap option. It's somewhere in the mid range of fast food places. I literally would not be able to afford to eat at McDonald's 365 days a year.

My setup costs are pretty much next to none, I pay a rent for fully furnished apartment with kitchen, pots and pans, tableware and everything included. Actually it would be a shame not to use them, those would be wasted expenses.

My cooking habits are opportunistic, if I'm at home, with no plans, I'll cook a meal and enjoy the process of doing so. A lot of the times I'm simply not home, so I don't even have the opportunity to cook.