This mainly occurs on org.
I have noticed players tend to accept a lot of "IOU" (meaning taking a service or product with a promise to pay back later). deals, and provide services for the promise of profits and shares.
While this element is common in an economy situation in the real world on the server it is a dangerous practice and can lead to many scams and people often end up being ripped off. It is often difficult to prove who owned what and to retrieve lost money and players end up short of cash.

I urge you guys to only accept trades where the person is paying upfront or do not trade. I would also stay clear of any deal that promises to pay you back in "profits" from a venture.

Never share valuables or rares. Use chestshops to lock up placed valuables (if you are unsure how I can make a small tutorial).

Record all trades and always make sure you get the items first (unless you trust your trader) before you pay as it is easier to retrieve items than money.

Be careful and safe trading

 

I actually do not understand myself why so many people do deals like this. Maybe coming from net where experienced players are very cautious...

Whatever it is Org is really about gaining wealth and using the skyblock island as a means to gain it. So there is a degree of greed sometimes. Money can make players do strange things.