well 99/1 rule... 99% of the product (visible bits) comes from 1% of the effort... but 99% of the effort and cost is required to deliver the last 1% of difficult soul crushing detail to get it done. The reason is that we optimize, align and facilitate organizationally the 99% because it's common.
(Game, chat app, anything.)
Well, large organizations have overhead for communication, management, etc (see v). But also there is a statistical effect - if we get many, many shots - sometimes we get lucky (in most cases - not; think of a typical hackathon project - usually it never gets properly started). So, in short, we see a huge survival bias.
...and it takes time to polish rough edges. For example, game Superhot started as a hackathon demo (with a single scene). It took Kickstarted crowdfunding, and a year of work to turn in into a fully-fledged commercially-viable game. (Personally, I think it is one of the most creative game ideas in the last years, especially for VR. I am happy that I crowdfunded it. :))