Having kids, while not a hobby, can certainly be expensive, and is probably the most obvious missing consideration here. It also makes a lot of other things less flexible, which tends to cost more money. (Want to go to a movie at night? Now there's a babysitter involved).
Kids aside, lots of things cost money. You like eating at nice restaurants? Money. Prefer to home cook nice meals? Great, equipment costs, therefore money. (And maybe ingredients).
Want to work out? Gym subscription or trainer = money. Buying your own home equipment = money. Want some form of cardio? Biking = buying a bike. Etc.
Nice clothes cost money. A nice TV costs money. Nice tech gear costs money. Etc.
And of course, travel costs a lot of money, depending on where you live.
There are obviously lots of other examples and hobbies. None of these are necessary. You can choose to be frugal with all of them, absolutely.
But - that's parent's point. Most people earning a relatively nice salary will naturally spend more money on nice stuff. That's partly because of natural tendencies to "use up" what we have, partly because of trying to be like other people, etc. But it's also partly because spending more money gives you nicer stuff / experiences, and people like them. And if you have the money, why not? There are reasons, but parent is right - you have to consciously choose to be different than normal and not spend money the way other people do when they can.