According to a global survey presently being conducted by BitcoinsInIreland.com, the preliminary results of which they have released (they will consider the survey finished when they've reached at least 1,000 respondents), the following are true about average Bitcoiners:
The survey is ongoing, and so far has encompassed over 50 countries, though a high number of those polled already (unsurprisingly) live in the United States.
The data set didn't make room for the many factors to why people may not use Bitcoin Core, but it can be guessed that most everyday Bitcoiners have no need of the full blockchain or the other features that Bitcoin Core offers. "Lightweight" clients such as Electrum and Multi-Bit have long since solved the problem of the lengthy downloading process, although the most recent edition of Bitcoin Core did speed up the Blockchain download by leaps and bounds.
CCN will post a full report of results when the survey is completed sometime in 2015. For more preliminary results, visit Bitcoins In Ireland.
Image from Shutterstock.