Whether a green card application is possible using only personal assets, not through investor immigration

I’d like to spend my retirement in Guam, a U.S. territory.

I have no intention of running any business in Guam after retiring — I’d just like to enjoy my retirement using the assets I already have.

I’d like to know how much in assets I’d need to demonstrate to apply for a green card using only my personal assets, rather than through investor immigration.