The nine demons were chosen at random from the ten thousand and nine players. There was no rhyme or reason to the selection, as it was just pure selection done at random by the systems once it was time for them to be revealed. They were a feature shown off for the Decagon and specifically told that only a select few beta testers would be chosen to be demons. The chosen and vetted beta testers, thinking that specifically selected meant that everyone would get a shot at becoming one, yet only the select few would be able to become demons. After all, they were having all beta testers come up with a demon design of their own. They were told which demon they would have to pick from amongst a pre-selected list of demons. Instead, they were allowed to create whatever demon they wanted, and they had true free rein over what it could be.
Red flags were raised for some people who made it this far and ended up getting rejected for questioning this aspect of the process too much. They were told that they were allowed to ask any question they wanted, but the answer they got could get them eliminated from the process. They wonder how was Kynatech developers going to be able to create ten thousand and nine different demons, as they were under the incorrect assumption that becoming a demon at some point was an ability that all beta testers would have the chance to gain the rights to. That was incorrect thinking, as it was specifically stated that only a select few would become demons. They really did mean that literally, as thinking otherwise would be on the beta testers, not them, regardless of how things looked otherwise.
Rather than everyone being given the chance and only the select few being able to ultimately succeed in becoming a demon. They had planned for the very start to only pick nine; they again truly meant that, and even out of ten thousand and nine people that still applied. "Only a select few" is an idiomatic phrase and a common expression that, while the exact number depends on a certain amount, that number itself is rather small, as even amongst a thousand, it normally only means at best a dozen. Not exactly a dozen, though, thus nine counts as within that range as a result. And so, while they had ten thousand and nine unique demon forms to choose from, they did not have to create one for each beta tester, as the reasoning the selection process took as long as it did was that the system was doing a number of things first:
Looking Through all the Entries
There were ten thousand and nine of them; thus, each one was looked at and examined in detail to see if it was even worthy of making the first cut at all. That first cut being the elimination process, as duplicates were not going to be allowed, as there would be nine unique demons. Thus, anyone who had selected demon forms that clashed was tossed right away. Also, typical selections were also tossed, as there was one exception bracket that was left open. The developer created it, hoping for a certain outcome from the one randomly selected from it. They were not going to force the beta tester's hand, nor was having this separate bracket for one demon really breaking the rules. All nine were still being selected randomly in the end. It is just one of the nine that would be selected from the one of the concepts that were rejected. Basically, a loser's bracket that allowed one of them to earn the right to be one of the nine still. However, they still had to be randomly selected from all those that were rejected at random, though.
Detail of Their Demon
A fully fleshed out design and outline was the next thing that their choice was subjected to. One could have the most unique idea there is; however, if there is nothing to support it, then it is just hollow on the inside. The system was looking for entries that not only had that wow factor of being unique, but also the substance to back it up as well. They were told this would be their own personal demon that would be what they created. If they did not create anything other than a name, that would be all it would be. Thus, the likelihood of it being chosen was extremely low, and it would be harmful to them in the long run. Inform them that, if they do not flesh out their demon, it will just have generic skills that can not be adapted and improved, as they are just generic skills. Many ignored this, which is why they were eliminated. Though the truly unique were allowed to stay in the running, as even if they were to be restricted to generic skills only, how they were to use them or the contexts in which they were to be used were considered unique enough.
No Non Demons Allowed
The word " demon " could mean a lot of things, and actually does not always mean an evil being, really. However, Kynatech and the developers had narrowed down their terminology so that the range was specific. They were not allowing beta testers to become Gods, as those were not Demons after all, nor could they become beings that were greater than Gods either. There was hierarchy within The Deacgon, and they were trying to give any beta testers an unfair advantage by having their pick exist outside of it from the start. However, they were not fully outright rejecting the idea if they were worded correctly or again had an interesting enough pitch to pass. Gods and Outer Gods were rejected immediately; however, they were fallen or former ones, which was a different story.
It was selection processes like these and numerous others that were happening in the background that were why the selection process for the nine demons did not happen immediately. The system needed that time to properly select the nine, as the developers did not want repeats, boring options, or too overpowered ones that threw things too out of balance.