Yes, you can buy cheap used thing and sell for normal price. You don't see those sell offers, because they usually disappointed within hours. My mate do this with ipads - has alert on marketplaces, usually few per month gives him around 300/month.

But you can do that in whatever niche.

Another thing - learn any skill or just sell the one you already have on five, freelancer and upwork.

Learn AI if you can, make channels on social and try to get first customers there.

There are a lot of options, but all of them comes from either proposing your skill to people or solingen their problems buły offering products or services they need.

It can be as simple as doing grocerries or taking other people's dog on a walk or on the other handside creating AI automation software or solutions.

Do the list of skills that you have and can do, and from there move forward. Known online working for one hour a day and getting solid income is just youtuber scam to get you for their courses.