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Twice my salary will not allow me to retire much earlier and sustain my level of living. Maybe ay 1M€/year that would be doable.

>>Brando+(OP)
If you don't increase your standard of living, it will. (Or the other caveats of course; assuming you're not already close to retirement, impending economic catastrophe or whatever).

Doubling salary post-tax will at the very least put you at a 50% savings rate, and that yields a time from zero to financial independence of 16.5 years. Assuming historically-similar stock market returns and a safe withdrawal rate of 4%. This relationship does not depend on absolute numbers beyond those stated above, only savings rate.

Most likely you'd not be starting from zero and having a positive savings rate already. Whether you'd be comfortable doing this is a different question. Many would never be, and hence never completely comfortable retiring.