He changed because Kennedy got killed
Reagan's conversion came from his marriage to Nancy Davis (his 2nd marriage) and the influence of his father-in-law, who was the father Reagan never had. (Reagan's father was an alcoholic and his relationship with him was somewhat complicated.) Dr. Loyal Davis was the most responsible for Reagan's political conversion. He also had a gig for General Electric in the 1950s where he gave speeches about communism vs. Ameicanism which was salesmanship for free market capitalism. By 1960 he was not a liberal Democrat anymore, although he didn't switch parties until either 1963 or 1964.
