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!

That's only if you dislike gardening. If you like it, you gain happiness from it (the opposite of a job). Once you have everything set up it's not that much time and money. It's like anything else, you get used to it and can eventually spend maybe 10 minutes per day watering (less if it rains).

Also, the food you get will taste much better because it's picked when it's ripe. Most vegetables in a grocery store are picked too early.