The Astros are another example of a team that the Cardinals can learn from. Immediately after winning the World Series, Houston went big and signed Jose Abreu to fill the void at first base left by the departure of Yuli Gurriel.
That deal hasn't worked out for them unfortunately, but it ultimately goes to show that they remained aggressive, even after winning the World Series. They wanted more, and so they went out and tried to improve their team instead of accepting regression. They even went out and re-acquired Justin Verlander at the trade deadline.
Another example is the trade for Gerrit Cole after the 2017 season. Houston already had a solid one-two punch in their rotation in Dallas Keuchel and Verlander, and this was after they won their first-ever World Series title.
But adding Cole gave them yet another ace in the hole, and it helped guide them to two more seasons of 100-plus wins and a second American League pennant. Houston refused to be complacent and ultimately chose the path that the Cardinals should be taking in the future.