Curious note I found while trying to validate your claim that current stock price is bargain: if you look at the stock price on Google for the past 5 days, the graph looks like a neural network tried to reproduce Tesla's logo.

Going back to your claim, I dont think a current price of $300 per share is bargain. But with his current behaviour, I can see that happening in the near future.

He'd bankrupt himself if he tried to do that. If the share price drops to low all his creditors will margin call him, which would wipe out the vast majority of his wealth.