This quote means that he exchanges what he does not want for something he does. Blindness means that you are lacking sight. Poverty means you are lacking money. Exchanging one for the other means you are getting out of a position of lack and stepping into abundance. You are gaining what you did not have previously.
You would use a comma. The semi colon acts when both what is in front and behind it can stand alone as a sentence. “With technology in the hands of so many people” does not make sense standing alone.
