The explanation to that is simple. For shoving other dragons off cliffs and forcing them to learn how to fly on their own. This technique was literally made to deal with young dragons too scared to jump off a cliff to learn to fly.....so they fire them into the air with magic and tell them to fly or die.
You all thought that this was a fantasy world isekai story of magic and dragons. It's actually all building to an isekai giant mecha story that will have massive space battles and decide the fate of the multiverse! All with an adorable waifu-house.
you know, now that i think of it...it's kinda amazing that MC never thought of making human-sized golems or even a golem waifu. it's like all his horniness get channeled to only his house.