What lesson is there for LeBron to have learned? The unstated premise of your comment is that this is a failure for him, but it’s false. He’s been to the finals seven straight years, with a good shot at making it eight next year with Cleveland. Then he could be off to the Lakers, who would be at the start of the same cycle.
It sounds to me like it’s been an extremely successful approach for him. You can debate whether it was worth it for the teams he’s joined, though they won’t give back the titles won.