People always say winning the jackpot will change their lives, but from what I have seen $50,000 will change a LOT of lives for ever. In Am.Me.Ri.Ca.
Give a person $200,000 and that may be just enough that they know they cannot make a mistake. Give them north of $500,000 and now they feel they can spend freely without a worry. Give them north of $1.5M and now they may literally think this money is a bottomless well.
Different scales and different 'changes'. You can give $50,000 to someone who has $10k/yr living expenses and it might change their life. But people with $10k/yr living expenses probably don't typically have the work experience and skill sets of your target demographic. When MacArthur finds someone who meets both criteria, well, that's great and a smaller award might even have more impact.
But if you are giving an award to someone with 6-figure salary and 5-figure annual living expenses, no $50,000 isn't going to make as much of a difference in their lives. If you want to seriously free that person from thinking about money for a significant period of time, it better be 7 figures. And anyway, $1.5M is not all that far from a bottomless well (i.e. 5% per year).
Give a person $200,000 and that may be just enough that they know they cannot make a mistake. Give them north of $500,000 and now they feel they can spend freely without a worry. Give them north of $1.5M and now they may literally think this money is a bottomless well.