How Do You Deal With a Windfall in Your 20s?

Mattea Roach still gets around Toronto by subway. In a city where tear-down bungalows can sell for $1 million, Ms. Roach, who uses they/them pronouns, still shares an apartment with their brother despite having more than enough money to buy a house.

For Ms. Roach, 24, the youngest ever “Jeopardy” super-champion, the $560,983 in winnings has done little to change how they live their daily life. They haven’t bought a car or splurged on…