How's everyone getting so many bells?

Seeing people with bells in the millions count after 5 days of gameplay absolutely astounds me. I've only got a meager 250k with one house loan payment done, and that was from selling nook tickets. Is tarantula farming really that much of a cash cow? Are there other ways that I don't know of to get so many bells? I've heard that there's an item duplication glitch but I'm still not sure how it works. If anyone has some good ways to get more bells, please let me know! I'm sure that you'll help me and other people out.

Honestly, stalk market is the only reason that I got so many bells! My Nook's Cranny was buying for 600. Just luck of the draw. Also hours and hours and hours of fishing and finding a weird large # of sturgeons and tuna fish for some reason, maybe just luck of the draw?? Idk. But this quarantine has had me playing nonstop so maybe that's everyone else's deal too.

(I definitely don't have near as many bells as some ppl have. I just have a few mil. I thought I was pretty rich but then I've seen people with like 20 million already so maybe I'm not. I'm very very suspicious that those people are the ones duping/cheating though lol.)

Abusing the stalk market
If one of my friends has a good turnip price we will have someone else go to sunday and jump between the two towns to buy and sell tons of turnips to make that profit