So in your world, the words "buying power" have no meaning? Because most assuredly, $10,000 in 1973 buys you a bit more than $50,000 does in 2016. Inflation is a real thing, even though it appears you just want to be pedantic.
He didn't say "buying power", he said "in actuality." I'm just saying that numbers have meanings like words.
In 1973, $10,000 was a massive prize to be won on a game show in the span of sixty seconds anyway, but it also comes on the heels of about fifteen years where the most any show gave away was a thousand dollars. The paradigm had shifted forever when "$10,000" became a prize on a game show again. Witness that Play for Keeps used thousand-dollar bills for bets on their pilot for a Winner Take All revival. They did so because that was the zeitgeist of the time. If they had started out with ten bucks nobody gives a darn.
In 2016 "$50,000" doesn't pop because we are over-exposed to massive jackpots. It's generally one step past a milestone, or an outright grand prize for something like Wipeout or Fear Factor. You would not say that Who Wants to be a Millionaire would have only had a top prize of $265,000 in 1973 because it purposefully neglects the history of the medium. In 1985 "$100,000" popped because to win it you either had to win a tournament of champions, back yourself and win eight games of Sale of the Century, overcome long odds to unlock your Dream House, or be the lucky soul who manages to climb the $100,000. In 2001 we mocked "Our first game of Twenty-one is for $100,000" because again it neglects that history that a huge cash prize is hard to win. $10k in 1973 might buy $55,000, but nobody cares that the top prize for the first victory in the winner's circle buys less than some index says forty years ago because it's still Fifty Thousand Dollars.