Like you said, there are many options with a psychology degree! The key for you degree to be "useful" is to have a passion for it! Depending on where you applied you can see the modules the university offers and from there see what careers paths this can relate to.
There are also plenty of jobs where higher education is required but they're not subject specific.
As a student who does international relations and international business I also get the occasional "isn't this a waste of time?" comments, but to me every moment learning these topic helps me grow as a human and lends itself to my passions and possible career paths.
So basically, look at yourself, your passions, possible career paths and what makes you happy. If you see psychology as a degree helping you with all of those then this is the right choice for you!
Hope this helps
~Michelle, placement student