Not really realistic for my hometown at least. I don't know any bank offering interest on saving deposits that is higher than 3%.

If I only didn't have to spend money on food and would save like 5000€ per year while earning the average salary in my town with 3% interest (which is already pretty optimistic) I'd have like 500,000€ in 50 years. While an average house would cost several million at that time (rn it's ~1 million €). I couldn't even buy a flat.