$1 Billion is a lot of money, enough to accomplish probably all the things you ever wanted. Dropping One Piece in exchange for 1Bil should be a no brainer.
However, most underestimate the people's love for a good story. Because of it, a multi-billion(?) industry like movie business exists.
Also, most overestimate how little $1 Million is and how fast it goes away. Is it worth dropping a good story? Probably. If you are smart enough, with 1Mil you could perhaps do something. If not, they are gone before you blink and you are back in the same situation, without One Piece this time.
There are exceptions tho, of course. Bad financial situation, cant feed your kid this month, cant pay for a surgery and many other scenarios... Yeah, dropping OP for a way less would be without hesitation in such cases. Luckily, I am not in such so I am not sure if I would drop OP for a million but for a billion, for sure. I wouldnt have time to regret it with so much money.