> Most software engineers in Europe probably don't even make €50K/yr
These two statements do not mix well together, if someone doesn't make 50k/yr it's unrealistic to expect to retire with 60k/year.
Let's see more realistic numbers. You make 50k/yr, getting 35k after taxes. COL is around 25k, but that varies wildly; with a partner and each one's COL is lower, but with kids and it's higher. Of those 25k/yr, 15k are for rent. You save 830/month, which gives you 630k after 25y, or 25k/yr at a safe 4% withdrawal rate (gross, so not enough).
But also let's say instead of paying rent you get a mortgage at that price, so when you own the place that is reduced drastically. Suddenly you find yourself with a COL of 12-15k/yr net, making 25k/yr gross from what you've saved previously.
Sure it's tight, but these numbers are without extreme sacrifice that you mention. Get lucky and make 60-70k/yr, or find a cheaper place, or inherit something (a lot more common in EU that USA I'd think), and it now seems possible.