For many people, he is a real disaster. People blame him for the current big dump in Bitcoin price. Whether the dump is mainly caused by him or not, but inf fact after he tweeted about "Tesla no longer accept BTC payment", the Bitcoin price constantly declined. Well, he is a smart guy and an experienced businessman, I am sure he has planned this since the beginning. His purpose seems just to get attention from people around the world by doing this.
It is true that we received a boost when Tesla announced that they will accept BTC. At that time, the exchange rate was around $40,000 per coin (the increase from $8,000 to $40,000 was mostly due to PayPal). When Tesla reversed it's stance, the prices went back to the previous levels. No real damage was done, as the dip was only temporary. The prices are slightly below $40K now, but I expect it to cross that level within the next few days. Tesla was always like a double edged sword. Their exit will not do much harm to BTC in the long run.