How did you get your start with the big money?
When I first started playing Stardew Valley (almost 2 years ago already!), and I got my first Crystalarium, I fell in love with it. I spent a long time grinding the Skull Cavern to obtain all the Iridium Ore I needed to craft over 10,000 of them, and I hired Robin to build me about 80 Big Sheds to house them. All Diamonds.
After several months of collecting Diamonds from them, I finally had hoarded enough (1,026,695) to sell, all at once, for 1,000,000,930 g. Before that, I had precisely 0 g. It was year 20.
So, in year 20, I was still absolutely broke, and then became a billionaire over night.
Anyway, I destroyed those Big Sheds and replaced them with 100 Fish Ponds, only to destroy THOSE and replace them with 130 Deluxe Coops.
My hope is that the 1.7 update will allow console players like myself (ps4) to purchase things more than 1 at a time, because that functionality is the only thing holding me back from sniping the title of "World's Richest."