Do the stalk market. I bug hunt only when I have less than 1 million.
turnips, buy like 150 of them in bunches of 10 and sell them at someone's town when the price is 500+ per turnip. I'm now bored of pushing turnips but back then, I would only sell at prices 600+. You can get close to 9 million bells in net profit from the whole trip
I believe there's a badge in it, yes.
Just remember: never TT back even a minute once you have them. Once blew every Bell I had because I TTed back an hour after forgetting that it spoils turnips. I don't want you to suffer the same thing.
Haha, that's why I haven't bothered with it yet! I'm terrible for forgetting things
Once you make that mistake one time, you'll never forget again.
Though you could just leave a bunch on the ground somewhere you'll see them all the time, to remind you that you still have them in your storage and need to sell them. That might help.