I wonder how the author is 100% sure that working in a startup is always better than working at Wall Street. I tried both ways, and there are ups and downs on b

I wonder how the author is 100% sure that working in a startup is always better than working at Wall Street. I tried both ways, and there are ups and downs on both sides, but I liked it just a tiny bit more in big finance (though not in big banks). Other people's mileages may also vary.