I retired with way too less money, had like 700k in my 2nd pillar. But anyhow, I went to Central America where live is cheap and you don’t need a heating system. Not even air condition at like 1000M over sea level where I did live, eternal spring.
But then something strange happened: I had more time for my stock market strategies and started to make real money there. Never ever in my live I made that much working. Should have stopped working at 20, not at 51… 
Actually I made that much money that I could even come back to live in Switzerland, the most expensive place in the universe. The tax laws here are better for stock market investors due to double tax treaties with the U.S. and no capital gains tax.
My assets are still growing at a fast pace, but I suppose I could lose easily 70% of the value of my stock portfolio and still have more than with what I started when FIREd.
And of course I had a lot of luck: I just left my house alone for 2 years and in this time a direct train to Zurich was added and they changed the construction zone of my land. I did good not selling then. Now I could lose 100% of my stock market investments and still be better off than 12 years ago when I FIREd.
I mean, what is the problem? In the worst of worse cases you have to work again, still better than having worked the whole time. I had a really good time the last 12 years and as I am getting old I probably will not have that much fun in the future.
No risk, no fun!
I don’t use ETF but build my own ETF with two mechanical strategies that I describe and log in this thread.