By the way, I wonder why Elon Musk has gotten some much into this presidential election so suddenly and so heavily supporting Trump for his second term.
Quite obvious. If the other side wins, it's going to be a living hell for him and all others who advocate for free speech, among other things. Trump is the better devil who could alsoQuote
Somehow and in some way Elon must be planning to profit off a second term for Trump, which still seems weird to me considering Trump himself has mocked electric vehicles while comparing them with gas vehicles, so this is kind of wacky.
Nothing wierd if you are a businessman. Both are businessmen 
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Do you believe there is a possibility Trump promised some governmental position within his administration in exchange of his big endorsement and the big money campaign he is doing for those who register?
He did promise him a big position, but I doubt if it's in exchange for the current campaign he's running because it's not specifically targeting the trump supporter.To be fair, the political left in the United States are pretty much in for the adoption of electrical vehicles, and innovation within that field, so I don't see why they would turn against him as a business person when his business completely allign with the vision of the future the democrat party has for the country, to lower the levels of contamination in the country and fight climate change overall.
Also, one needs to see those big 1 million checks from the opting of a person who may not be explicitly in for voting for Donald Trump in a few days. Let us imagine some independent voter wants to participate in that give away for the chance of getting money, he signs the stuff after getting registered and applies for the lottery, by pure chance he gets selected and gets to meet Donald Trump and Elon Musk personally giving him one million dollars, there is a pretty high chance that independent voter turns into a Trump voter, only by the sympathy created in such a life changing experience. Even if the vote is secret, that person would feel the need to "give something back" for the money he received.
Even people in the audience who did not win the money could still vote for Trump out of the sympathy of such contest/lottery.