If so, why would one automatically assume Musk has the bad advice and the rest of them have good advice? It's awfully ironic as science is literally the process of demonstrating the widely-accepted wisdom (preeminent theory) wrong.

Do you want to take a risk of going down the history as the society who estranged Galileo? Even the haters secretly know that the likelihood of Musk being remembered in history books is higher than a random FRS. In fact, that's likely why they are jealous and eager to write such letters.