I think it would have been much cooler and more close to the setting this manga tried to sell if the main character actually really did have all the useless skills, and all this strength he has now was his own effort and growth with the help of those useless skills that somewhat helped him at the beginning to gain a stable footing quickly...so when the plunderer came, they won't be able to steal anything of importance from him since his given skills are all weak ass ones that don't matter anymore and his overpoweredness is his own strength now.
But what a shame. It completely deviated from what I thought it was going to be when I read the summary.