The Cavs didn't even have enough to offer LeBron a max deal absent having his Bird rights, and they had zilch in the way of trade assets. So, in order to "make it happen", LeBron would have had to play for peanuts and convince the other 2 to do the same so that they could all 3 fit into 9-10 million dollars of total cap space, or convince Toronto and Miami to take virtually nothing in return for enabling their best players to go to a team that couldn't sign them otherwise.
You want to say he shouldn't have left Cleveland regardless, that's fine, it's your opinion. But Bosh and Wade coming to Cleveland wasn't going to happen, and even just one of them coming was extremely improbable. Going back to Cleveland would have been going back to more of the same.