The Titanic director has made 33 dives to the shipwreck and visited ocean depths in a submersible he built himself. He compares OceanGate to the Titanic in that both ignored safety warnings.
And yet not 2 posts up you quote Cameron in a way that makes him sound like he has significant knowledge about the structural integrity and construction of a high pressure tolerant vessel.
It's not clear what you are trying to say. He obviously funded it and piloted it and had to be intimately involved in its construction, including oversight and planning. He took the thing down to the bottom of the Mariana Trench. Are you arguing that he doesn't know as much about the construction of the sub as a guy welding a joint or tightening a bolt? I'm pretty sure that most people would say that if you could name one person that "built" the sub it would be him. He is arguably the world's expert on this topic.