To learn the skills, he needed a lot of skill books and skill crystals.
He can get the common ones, but to get rare ones, he has to attend auctions and search through various shops to get the 500 skills.
It will definitely take weeks to do that if he wanted to hide his identity when buying the skills.
'I have to hide my identity until I am sure to overpower everyone,' he thought and pondered about his second option to create a skill.
There is no mention of what kind of skill or what tier of skill is needed to create.
It means it will be okay as long as he makes a normal skill with low tier, but to do that, he needed at least A-class knowledge books first.
The books he got from the cave only possess master level knowledge that weren't enough for him.
"Anyway, I should first get used to my levels. I will think of this later," he muttered with a sigh and continued to use skills while also pondering how to create one.