NBA

Made the 3 point shot a regular thing. In the previous generation, the 3 point shot was generally reserved for specialist shooters on the team as it was deemed a low percentage shot. Today, everyone is shooting 3s at a high clip, and almost all players on the floor take those shots regularly.

He really was just so much more efficient at shooting from beyond the 3 point line it changed the landscape of the game.

If you look at 3pt attempts over time and 3% percentages over time there's a massive spike after Steph. The introduction of analytics plays a small role as well, a lot of shots used to be taken 2'-4' before the 3 pt line it which has largely died (just take a step back and take the 3 for an extra point)

Steph really just showed what's truly possible when shooting from deep and the entire game changes. Growing up playing in Highschool 3s were considered "bad" shots for a lot of players. Nowadays most highschool players are taking 3s and relatively efficiently as well.