It depends what you're looking for in a wardrobe. I've managed to cobble together a decent-quality, well-rounded wardrobe of staples during the past two years of thrifting—though my style leans toward American trad, and I wear a lot of Brooks Brothers and similar brands that are relatively abundant. I've been very selective about condition, fit, and styling.
That said, I've sunk a lot of time and effort into this, and it would have been easier shopping online. I've enjoyed doing it this way though.
Yeah, I just straight up disagree with Mainy and Klobber. My closet currently has 4 solid gray suits, 3 solid blue suits, and double that many each blue and gray pinstripe suits -- solid staples. All are dual or single vented, high lapels, most flat front and some with ticket pocket, and all are Samuelsohn or better. If "high end" means only Kiton, then yeah, but that's a function of not finding KITON very often. Did I have to pay a little more for some of these than the standard thrift store $10? Yes. Did I have to be patient and/or lucky? Absolutely. Did I find all of them myself? Of course not; everybody here's closet has the fingerprints of other members, but that's why we love the thread. Did I have to use Oxy on all the white shirts and many of the others? Yessir. But unless we're playing "troll the noob" and I missed the memo, I simply disagree with the notion you can't build a comprehensive wardrobe (including basics) via thrifting.