Right, even if he didn't have any of his inventions, the MC is born into nobility. His parents not only have their own magical tool business, but also have their own fiefdom. He'll find a reason, one way or another, to avoid getting married.The real kick in the crotch is that the MC would still be filthy rich even if he had a wife and a couple kids.
Surely not as rich, nor able to buy as many 300mill artifacts without having to consult his bank book. But just the coffee mills alone should be making bank, and that completely ignores all the other specialty creations he produces on commission.