As a developer, and manager of technical teams, there is definitely a tendency to be ridiculously optimistic about your own, and others, capabilities to deliver. As you note timeline estimates are often WAY off the mark. Even adding an error allowance of 100% to developer estimates will prove insufficient. It just takes some hiccups in testing to unravel the best planning.

As to Cardano, their challenge will be remaining relevant while other sovereign chains surpass their functionality. There are still many fans though the community has suffered considerable flux over the past 5 years. Personally, I think they have a high risk of becoming out-dated.