Sure, it's possible to generate truly passive income, without any ongoing work to sustain it, but such projects are so rare that it's impractical to pursue them. It's like saying you're going to create the next unicorn...good luck with that.
99.9% of endeavors worth doing pursuing require some level of constant work to continue capturing the value they generate.
I say this as someone who made his first few 'passive' dollars LAST NIGHT WHILE I WAS SLEEPING. But I put 'passive' in quotes because this was after 5 months of working for nothing, and the grueling work required to keep my offering attractive continues.