Is it, though? I mean, yeah, it's no Google or Bing or Yahoo, but it also doesn't have Google or Microsoft or Yahoo money, either.
It's on the brink of breaking 1% in the US [1]; that might seem small, but that'd be a good 33% of ChromeOS users or 10% of macOS users. Not bad, considering.
And really, blaming DuckDuckGo's branding for its poor marketshare is pretty ridiculous given the competition. I mean come on, what kind of a name is "Google"? Or "Bing"? Or "Yahoo"? The ridiculousness of the branding doesn't seem to actually be a problem, since that's actually constant across all of the top four browsers in the US.
[1]: http://gs.statcounter.com/search-engine-market-share/all/uni...
[2]: http://gs.statcounter.com/os-market-share/all/united-states-...
Search engines are a mature market. You're not going to displace Google unless you manage to disrupt the entire industry somehow; social tried and failed at this, so it's not clear what this would even mean at present.
As a challenger in a mature market, DDG has the right strategy, and they are playing their hand successfully. I seriously doubt that branding is holding them back.