Upvote:3
Hawaii is a US state because Hawaii is economically and geopolitically stronger and safer as part of the USA than as an independent nation.
Wikipedia summarizes the mechanism by which HI was brought into the USA.
This question seems to be based on the assumption that
"if an island were to truly belong to you, then this you suppose to have it for many thousands of years"
I can find no evidence supporting this hypothesis. I'm not even sure that I can find a legitimate example; off the top of my head I can't think of a single political entity that has survived for many thousands of years, which would result in all islands being free and independent states. (which would inevitably result in the conquest of those islands in short order).