Saving massive amount of money? Judging just from demographic that uses hackernews (mostly tech workers), I think it's actually cheaper to eat out if you measure price of your time by how much money would you earn in that time while working compared to shopping for the ingredients, cooking and doing dishes.
That's an optimization that looks good in theory but is poor in practice. Evidence has proven that we consume more calories at restaurants than we do when we cook at home. There's a lot more to get out of cooking at home than nutrition, though. As others have alluded to, the experience of cooking and working with your hands is excellent (and cheap) therapy.
As for economy, you will find it once you've built up a good stock of spices and non-perishables and begin to optimize things by--for example--making chicken stock from the bones of that bird you roasted for dinner, or freezing the extra tomato paste from the can that you used 1/3 of.
This is coming from a guy who spent the first 15 years of his tech career eating out every single meal before meeting a girl, getting married, and then eating 6 of 7 weekly dinners at home.
My doctor tells me the secret to long life includes not eating out too often. Which is short for restaurants tend to cook in ways you wouldn't at home: deep fried food is much more common. They tend to use more salt than I would. Sugar is added to things that don't need it. Cheap oils instead of the better quality ones...
I'm a salaried employee, I don't get paid extra if I stay an hour later and get a takeaway on my way home, and I still have to pay for the takeaway. I get the idea, but you can't work 24/7
I've been there, done that. It's not worth the extra $20-30k/year to do nothing but code. Even if I had clients to fill 80 hours a week I would still only work 40. Life is too short to do nothing but earn money.
If I go to H-E-B and buy a rib eye steak for $15.99 a pound and cook it. I'm out less than $15.99, because I don't want a pound of steak. If I go to a mid range steak restaurant I'm going to get a rib-eye for $29.99 for 12 oz of steak. And it's going to be of lower grade and less seasoned. Why would I do that?
Also, I'm not working all the time. Cooking is a way of relaxing.
Even if I charge $250/hour I'll still save both money and time when doing grocery shopping and meal prepping every sunday night. It's not like I'd been working on a sunday night anyway so I can't count those 5-6 hours/month spent on grocery shopping and cooking as a "loss of income".