Conned

[Dianne]

When a person decides to make a deal presented to them by someone else because they are convinced they will benefit [handsomely] from it; but [the deal] results in said person losing everything they put into it plus [invariably] much more, all while the someone who proposed the deal is on track to benefit immensely, and secretly was the only one guaranteed to benefit at all.

[Lanell]

past simple and past participle of con informal