Depends what you mean by useless.
There are a LOT of degrees that don't lead directly to jobs in the field (Arts, Journalism, Communications etc.)
And then there are degrees that do lead directly to a field which are more or less engineering, medicine, accounting, actuarial studies etc.
But society today is so corrupt that there are a lot of jobs that just require you have a degree in something, whether it be journalism, medecine co-op or gender studies.
So getting a degree in journalism is useless in the sense that it doesn't determine a path for you or anything like STEM.
However, it is still useful in many job settings due to progressive credentialism (shame but true).
So it's up to you, you can go to uni for 3 years, study journalism hard and get a degree that will put you in the same boat as everyone else.
Or you can go into STEM, study hard and know that you'll get something out of it.
Or you can skip Uni, and take complete responsibility of your own learning.
For journalism, if you have the idea of become a journalist, whatever you do, start a blog. Do what journalists do, write about current issues.
Uni will teach you all the theoretical stuff, but in the real world no one cares about that if you can't even start a blog. Do journalist's need a degree in journalism ? If not, why do you want one ?
I'm a math major, so I'd solve the problem like this. Either you study Journalism or you study in STEM or you don't go to Uni. Look at what you'll have to do in each scenario, what the costs will be and then weigh that up against what you'd think you'd get in the end.
As for the double degree idea, if want to learn journalism for the sake of learning, why not self-teach yourself ? If there's something in the degree itself you want, then I'd recommend postponing it until later. Get a degree in STEM or don't get a degree at all, and then once you've settled down in the world, then go do a masters or whatever for intellectual fulfilment. Beware though, once you go into STEM, you're gonna be pretty busy. It's not lucrative for no reason after all...
Personally, I don't think journalism is worth it, but it's up to you.