I would agree that a very large percentage are TSLA owners. This does present some interesting points for anyone who wants to short TSLA. Here is my idea. Most TSLA owners are fairly well off financially in order to be able to own a Tesla. If a large percentage of these owners are also TSLA owners, then a significant percent of the float is owned by wealthy owners of the car. These people are the ultimate insiders since they actually have the car, know everything about it, know how good the service it, etc. So when there is a negative news story, they don't have the knee-jerk reaction to sell their shares. Therefore, it this is a cushion for large drops in the stock price.
A more interesting question would be how many TSLA owners have had the stock appreciation pay for their car. I know I got my P85 for "free" and then some because of the stock I bought on IPO day.