Probably? Not necessarily.
Whilst I believe that they probably exist, there is a strong argument which is along the lines of, if they do exist then why haven't we seen any yet?
There are a variety of answers to Fermi's Paradox (which is what the argument you're refering to is usually called). It's not really a paradox.
The simplest answer is one of scale:
If a civilisation explored a million stellar systems per year, it would take in the region of 100,000,000,000,000,000 years for it to explore the observable universe. Which is about 700,000,000 times as long as the universe has existed for.
Even if they were actively scanning for other civilisations, the sheer scale of the observable universe would be against them looking here from close enough to here and within the last century.
Even that is assuming that their observable universe overlaps ours. Maybe it doesn't. Maybe the universe is bigger than we can observe and they're >13.8 billion lightyears away from us.
There are various other answers.
Maybe they're not looking for other civilisations and not exploring much. Perhaps there are civilisations spanning one or a few stellar systems and content with stability or slow expansion. Given the scale of the universe, a vast civilisation of a million stars would take up a miniscule part of the observable universe.
Maybe hardly any civilisations survive long enough to scan more than a tiny part of the universe a little bit. There are many ways to extinction.
Maybe there aren't any around right now. Perhaps there were advanced civilisations a billion years ago that have since died out.
Maybe we're amongst the first generation of civilisations. Conditions in the universe were unsuitable for life for a very long time (and still are in many places). Perhaps there are other civilisations out there but they are at roughly the same level of technology that we are. Maybe we're the first species to get this far. Perhaps the next most advanced life in the universe is at the same sort of level as homo erectus. Or maybe only single-celled organisms.
Maybe they know we exist but want to avoid contact with us, either because they think our societies are so messed up that we'd contaminate theirs or because they think that contact with them would ruin us. Star Trek's Prime Directive wasn't random nonsense made up to be a plot device.