That last one is unforgivable.
The last three are horseshit.
Say what you will about the morality of the other but at least they are reasonably likely to actually work.
The last three are not.
Crypto is insane horseshit unless you are running a scam, which at best is a huge amount of effort and at worst is oops time to flee to thailand.
Drop shipping and ‘picking’ is basically boomer nonsense that requires a huge investment of time, space and money to conceivably make it worthwhile, and it almost always goes wrong, and you end up with a garage or storage unit full of useless crap that won’t sell either at all, or for a profit.
There are so many ways you can get fucked as a buyer or seller on eBay, its ludicrous.
Flipping second-hand goods hasn’t been viable at any worthwhile scale in over a decade. Too many people know how to use the Internet now, and usually google their shit before it goes on the garage sale or flea market table. The days of finding that rare vase or vintage toy that the owner doesn’t know the value of are gone.
As the other commenter mention, yes Estate sales and other kinds of government auctions / sales of things like repo’d property or good can be a decent way to find deals as buyer…
…but flipping them is not likely to earn you much.
Only form of profitable mass reselling I am aware of is when you’re selling goods stolen from mass retail theft, lol.
Estate sales. It’s just a bank or company selling a deceased person’s stuff to cover costs or save them the hassle of getting rid of it. You can get some premium stuff for cheap because it’s not worth the effort to them to do otherwise. Girlfriend found some particular figurines for 25% of what they were worth, but because they’re not a common collector item (and there were a TON) it’s easier to sell cheap than hold out for the real value.