This is an interesting point.
What is your opinion, why tha 4% withdrawal rate is based on US assumptions, and why for an European it may not be valid?
Than what if you move to ex. South-America from the US?
"One thing for us all to keep in mind is that the 4% safe withdrawal rate we usually assume around here is based on US assumptions. For a European, they may not be valid."
First of all, the
Trinity Study, from which the 4% safe withdrawal rate comes, was done by a US university and based on analysis of the US market.
Second, the US economy is a large fraction of the world economy, which means that US investors who invest in the US stock market are already relatively globally diversified. It also means that they can get such diversification while owning funds denominated in the same currency that they spend (i.e., US dollars).
For a non-US investor, it's different. You have two choices: you can invest in your own country's market (denominated in the local currency) and accept higher lack-of-diversification risk, or you can invest in the US market and accept all the same risks as US investors
plus currency risk.
Third, historical returns for most other countries' markets have been
lower* than historical returns for the US market. "Past performance does not guarantee future results," as they say, and there may be some good reasons to think the US's previous outperformance is not sustainable (e.g., maybe the outperformance was in part due to the US being the last [capitalist] country standing after WW2),
but then again, maybe there are structural (or geopolitical) factors that might cause the US's outperformance to continue.
The EU economy is almost as big as the US's and (hopefully without turning this into a political discussion) I'd say it is similarly-well run and good for business, so I don't think an EU investor investing in EU-denominated securities would necessarily be at a disadvantage compared to a US investor. However, the outcome is certain to be at least
different.
(* note: this link shows that Australia and South Africa have done even better than the US, but it's important to remember that they're also much smaller and much less diversified.)