Immortality sounds nice, but many may not want to be on earth forever, they would want to move on eventually to other planets, or maybe be in a different form or shape. Imagine being on earth for millions of years, you’d get tired of eating the same stuff every day. It could work if you slept for years at a time probably, and new foods, inventions, ways of travel came around, but us humans do not like repetition for evolutionary reasons.