$80k will give you one year of very comfortable life in Central Europe. If you want to live in an international city in a decent flat 4 years is not realistic, more like 2.
I live in Poland in a city center in a metro area of 2 million people on $9k per year. That's rent free, because I own the place, adding rent would push the total cost to $13k per year. That's six years of living on $80k.
Also, I'm 42 and retired :) It's really easy to retire here when making software money.
If you are willing to forgo a car, expensive food and be fine with a small studio, you can easily do 4 years on $80k in central Europe. You can do 10 years in many parts of the worlds and it'll require some adjustments but some places (ie: Vietnam) can be really okay and offer a night life unmatched by the US.
I'm afraid you underestimate rent costs. In smaller cities you may still find something nice for ~900 usd per month, in more popular places like Krakow, Prague ~1500 usd is more realistic but still optimistic.
This feels incredibly out of touch with reality. Since you mentioned Prague, the average salary in the Czech Republic is roughly $20k per year, and that's the average, plenty of people take home considerably less. You're saying $80k is not enough for more than a year, how do you think all those people manage to get by?
1500 usd for Prague with bills included. Rent in Prague in a very good location is about 1000 eur. The bills can be about 400. For 1500 usd as rent you're looking at some very fancy places.