I missed the AMA but I'll ask this here since people seem to be in the know. In the beginning, Spacex and the original merlin seemed to be all low tech, get it

I missed the AMA but I'll ask this here since people seem to be in the know. In the beginning, Spacex and the original merlin seemed to be all low tech, get it done (ie the merlin was ablative cooled chamber and nozzle). Now the ITS engine is super advanced. I always wondered, why the turn around, and has Musk ever written or said anything about Truax's Sea Dragon[1] concept? [1] https://en.wikipedia.org/wiki/Sea_Dragon_(rocket) https://en.wikipedia.org/wiki/Sea_Dragon_(rocket)