During covid lockdown, I discovered I really only have to go to the grocery store once every 1-2 months for all products except fresh produce, which require weekly trips. Once I started my own garden I got a lot of time savings back by cutting out >75% of my grocery trips, and I found myself using fresh herbs much more often as they are always available just outside my kitchen for last-minute additions to recipes (vs having to plan ahead and buy those expensive little packets at the store). I also started eating a lot more leafy greens; I'd stopped buying them because I was tired of constantly throwing them away after they went bad in the fridge after a few days, whereas they stay fresh on the plant for weeks or months.
So actually, I grow a garden because of the time savings. Well that and because it's fun to play in the dirt, not to mention it's a great non-sedentary hobby that gets me outside more often. Plus practicing food self-sufficiency is a useful skill to have. And since I garden in my front yard it's an excellent ice breaker for getting to know neighbors and other folks in the neighborhood. Basically there are a bunch of reasons to garden beyond the food you harvest!