Minority representation is actually slightly higher in cybersecurity – 26% - than in the US workforce overall, which is 21%. But disparity in salaries and management roles for underrepresented groups remains a common theme, even for an industry that faces a shortfall of some 1.8 million unfilled security positions worldwide by 2020, according to data from Frost & Sullivan.
What perhaps would a more revealing deeper dive is to examine educational and financial hurdles in entering the cybersecurity workforce rather than the demographic makeup. One of the challenges we face in the U.S. is that starting in the 1980s or so, our secondary education became very focused on preparing students to enter liberal arts colleges. What disappeared from curricula were technical programs - excellent pre-engineering training - while also essentially putting every high school student on a career path to debt to pay for four-year college degrees. As such, for those of limited means, their path to well paying technical jobs were blocked by either a lack of public education or an undue commitment of both time (four years) and money (tuition) to enter the workforce. While STEM initiatives have started to bring back some engineering into schools, I still find it directed at pushing kids toward four-year degrees and even graduate education more so than practical technical education that can turn them into a wage earner. If you are familiar with Mike Rowe's "Profoundly Disconnected" initiative there do seem to be some efforts to stem (no pun) this tide. My larger point is that for someone of limited means, it takes them longer (a four year degree might be seven years because they must work and go to school) to enter the professional workforce. This hurdle not only diminishes their representation (because it is a barrier to entry), it also means that by the time they enter the profession they are well behind their peers.
Now, if people of limited means seem to share a similar demographic makeup, that's another (albeit related) kettle of fish.
As a footnote, I'd caution that many find the term "Caucasian" questionable. If you research it, you will find its context is a very narrow view of race (we all fall into one of three buckets), and that the two-thirds of that view has been eliminated from our lexicon due its being construed offensive.
Along a similar vein, often these demographic comparison are incomplete or artificial. For example people of Russian lineage often have a hard time finding the right box as they could be technically "Asian" even though often they are lumped into same category as those of western-European descent. Similarly, Haitians are often mislabeled as African-Americans instead of "Caribbean" or something more accurate. What often happens is that people of western-European, eastern-European and even middle-Eastern descent are often painted lumped into the same category even though a generation or two ahead of them were persecuted (even murdered) by ancestors of those in the same category based entirely on ethnicity. So on and so forth.