Few million?

I would be set for the rest of my life if I got half a mill falling from sky today, I guess I could even make it work with 250k.

Currently I am pondering how absurd amount of money a billion of dollars is. When loads of people can only -earn and eat through/spend not save- $1 million; working their asses off for something like 20 years.

For what it is worth, if you want your withdrawals to last for decades, then you are limited to around a yearly inflation-adjusted cap of around 3% of the original principal per year, gross of taxes, if you invest in low-cost passive index funds. That is a budget of $30K/year for every million you have invested in the market.

If you are interested, the /r/fire and /r/financialindependence subreddits are useful.