1) There was a data flywheel effect, wherein Google was able to improve search results by analyzing the vast amount of user activity on its site.
2) There were real economies of scale in managing the cost of data centers and servers
3) Their advertising business model benefited from network effects, wherein advertisers don't want to bother giving money to a search engine with a much smaller user base. This profitability funded R&D that competitors couldn't match.
There are probably more that I'm missing, but I think the primary takeaway is that Google's scale, in and of itself, led to a better product.
Can the same be said for OpenAI? I can't think of any strong economies of scale or network effects for them, but maybe I'm missing something. Put another way, how does OpenAI's product or business model get significantly better as more people use their service?