I'm a millenial but not one of those people you're describing, and I have actually paid my condo off.

The keys for me:

• No kids
• I job hopped in (what at least used to be) a high-paying field (tech)
• I moved job markets from a low COL (cost of living) market to a high COL market
• No student loan debt for me (my mommy and daddy paid for my tuition to a local state school 🫶 ), minimal student loan debt from my wife (~5k)...which I paid off after we got married
• I don't give a shit about cars...I drove used cars until I could comfortably buy a new one cash
• We only have one car between the two of us
• I moved rather than paying higher rents, and I often lived in really crappy apartments because they were cheaper (I do not recommend btb)

Healthy helping of luck involved, and definitely support from my parents by way of room and board until I was like 23, tuition, small car loan of ~8k after I graduated. However, I paid them back in full for the car, and I'm the only one of my siblings not to hit up Mommy and Daddy regularly like an ATM. I fucking hate debt with a passion (or even really temporarily owing someone else anything) and have basically never carried large amounts of it outside of when I had my mortgage for my condo.

(My neuroticism around debt is probably why I paid off a historically low rate mortgage...if I would've sunk that into the stock market or something instead of paying it off I probably would've made a fortune.)