I guess they could also have lost an almost equally insane amount if things had gone south?
The reason you can make so much with so little capital is that the probability of the stock price moving above strike price of the call option is low assuming that the strike price is much higher than the current price and the expiration date is soon
Today they were selling for ~$85/share. But on Jan 1 they were selling for ~$5/share, and tomorrow morning it looks like they will be worth maybe $150/share.
30x in a month for a True Believer -- sure wish I had done it!
[1] - https://www.marketwatch.com/investing/stock/tsla/option/TSLA...