Uber has multiple moats: The mutually supporting networks of drivers and riders, as well as the regulatory overhead of establishing operations throughout their many markets.

OpenAI is an API you put text into and get text out of. As soon as someone makes a better model, customers can easily swap out OpenAI. In fact they are probably already doing so, trying out different models or optimizing for cost.

The backing isn’t a moat. They can outspend rivals and maintain a lead for now, but their model is likely being extensively reverse engineered, I highly doubt they are years ahead of rivals.

Backers want to cash out eventually, there’s not going to be any point where OpenAI is going to crowd out other market participants.