Retiring at 50 is extremely risky in terms of sequence risk[0], so you'd want a low withdrawal rate on your pot. You're also likely to want a higher income initially while you're still young enough to enjoy it.
So let's say your target is €2M for a €60K/yr income until you die, after a 25 year career. That gives you a couple years of fucking around after college / some bad years / gaps.
To achieve that over a 25 year, investing in to a smooth 7%/yr bull market, you're going to need to invest €2,500/mo. That's something along the lines of €50K/yr of gross income (assuming 40% tax).
Most software engineers in Europe probably don't even make €50K/yr... and we haven't even taken in to account taxes on gains, raising kids, buying property, or just enjoying life throughout your career!