The same that happened to everything else . . . ..when I learned to fly gliders in the Washington, DC area in 1966, it cost ca. $450 (from a commercial gliding operation) for training to the PPL(G) level, or about 4.3% of my gross household annual income at that time. Today, in my club, it'll cost a new member about $2000 (not counting his Club initiation fee of $500) to get the same rating with about the same amount of actual flight time, or about 2.2% of the average gross household income in our demographic area. By 1995, I'd paid more for the two cars in my garage than I'd paid, in 1968, for the house in which they 'lived'!! Hey, prices change for everything!
I don't think it's the price of soaring that turns people off so much as it's just changing priorities for what they want to invest their time/money in.
Jim Kellett Resident Curmudgeon Skyline Soaring Club
http://skylinesoaring.org/