You definitely save money eating at home once you get good at it. If you live with someone else it is also a great social opportunity. These days I cook and eat with my wife, but before I met her I cooked with my roommates.
One roommate now will only eat with us if we add up the cost of ingredients and charge him fairly. Many of our dinners cost only a couple dollars.
Pasta with marinara sauce and dinner rolls: 1.33 / pound pasta, 1.80 jar of sauce, rolls 0.13 each. Serves 3-4 people for $5. 15 minutes (limited by water heating).
Tacos with guacamole: $3 pre-made guacamole, tortillas 0.5 / 12 pieces, beans 1.20 / can, salsa $2 / half bottle, tofu 1.5 / block, cilantro 1 / bundle. rice ~$1. Serves 3-4 people for $10. 20 minutes (lots of tasks, have to cook tortillas).
I won't break it down, but I can do a nice sushi dinner: various rolls, cold tofu, inari, miso soup, for 3-4 people for about $15. 45 minutes (lots of tasks).
In any case I can feed three adults for about ten dollars and 2/3 of an hour of my time. Usually there are enough left-overs to make a nice lunch for myself.
I enjoy eating out, and do so about once a week. Before I got married I ate out a lot. I would spend about $900 per month just for myself. Now I make an effort to cook dinner 6 days a week and spend a total of about 800 per month on food for both of us.