@jorian The reason you think you're still lower middle class is lifestyle creep.
You buy a house at $40k a year, for example lets say a $100k house. You only make $40k a year so you buy a nice inexpensive used car thats already paid off and your idea of going out to eat somewhere nice is applebees. You get by and you're happy.
Its 5 years down the road, you get a raise, now you're making $75k a year and you're ecstatic because you're making almost double what you were making 5 years before and by comparison you're bringing in $1000 per pay check more after taxes than just 5 years before.
Wowee thats good!
Buuuuuuut that used car is getting long in the tooth, better buy a new one. There goes $500 a month.
Also the house is getting a little cramped.....better upgrade that... there goes another $400 a month.
But hey its okay because you are making about $2000 a month more! Buuuuuut you don't really consider applebees fancy anymore, now Longhorn steakhouse is fancy, and you don't really have time to cook like you want so you order doordash 4 times a week and on fridays you go to longhorns. Also your new coworkers like to have happy hour every thursday and thats about $75 per.
All of the sudden you realize that you're in the same boat as you were in when you were making $40k.
Its wash rinse repeat all the way from $40k to $150k.
Its little things here and there. It become super easy to justify bad spending habits when your income is going up and sometimes it makes sense and sometimes you take a step back and go "Holy shit, we really do eat at our favorite sushi place 6x a month and each time is $75+ what are we doing?"