I am speaking about spending habits, you seem to be talking about relative cost of life events. I don't have kids but kids are usually not what people are referring to since kids are a cost increase for all parties, rich and poor.

Basically, if I usually buy a certain Ikea table if I need a table, I still buy that Ikea table, and it still feels too expensive to me, regardless of the fact that I earn a lot more now. If I get an apartment that I like, I don't have any desire to get a more expensive one. I only want a more expensive one if the current one is really bothering me for some reason. I'm still uncomfortable with purchases of certain amounts, or buying things for myself in general (particularly, clothes and furniture). It's physically painful to spend certain amounts of money.

There's a set point in my brain for how things are supposed to cost, and that point is very hard to move. I.e., it takes actual effort to explain to my brain that I can spend more now. There's nothing automatic like the general wisdom suggests.