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You ever notice how despite getting hit with hurricanes every year most of the coastal cities in the US don't need to be completely rebuilt? According to this article on Statista, about 300 people in the US died from hurricanes between 2016 and 2020 and that's on the high side for a 5 year span. Definitely tragic either way, but definitely a price worth paying for all of the benefits coastal living generates for a society.
Living on coasts or close to bodies of water is what allowed people to do international trade. Coastal cities, especially the big port cities which supported expeditions, are the reason we have modern science, medicine, food, trade, cultural exchange, etc. >

I think if your thesis was “it is a mistake to continue to settle and build on the coast” I would agree with you, but since your argument is “it was a mistake for human beings to live on the coast in the first place” I’m going to disagree. I the world was settled by seafaring people as well as land walking people. How many island nations would be completely empty if we just decided to stick to the mainland and away from the coast? How much trade, both of material, goods and ideas, wouldn’t have happened if we haven’t settled on the coast. 
Not all things have to happen for all time. Sometimes things come to an end, that were very good for a time. I think it’s perfectly OK to acknowledge that you need to change something moving forward, while also enjoying the benefits that something brought you in the past. >

This argument speaks to the need to carry forth historical progress via recogniztion of how obsolete systems no longer benefit us, which is important. My thesis was so extreme because I was thinking of events like the 1700 Cascadia quake. >

Even today a massive amount of trade happens at seaports. By value, 53% of US international imports come through seaports. That's hardly obsolete. And of course having seaports that handle hundreds of billions of dollars in international trade in turn requires labor for the ports, intermodal stations, etc. And that labor in turn has other needs like food, housing, entertainment, etc. which lead to other industries being present in port cities, at the very least to support labor related to seaport trade.
Maybe there's an argument that we should try to minimize how much industry develops around seaports and try to keep it to industries that directly rely on the ports, but that requires some pretty serious central planning, which generally doesn't end well. >

Tsunamis and hurricanes do not frequently happen on every single coast in the world. They are, in fact, relatively rare, especially before global warning.