Be sure to check the timeframes involved. Creatine is a naturally produced in your body, and you also get some from diet. Your body reaches saturation at a rate that varies by person. Some people will see near to 0 benefit from creatine as their body is already producing a near maximal amount of it. But even for those with low creatine levels, a brief loading phase (of ~25g a day for a week) and then 5g a day maintenance will generally see them at peak levels.

There's probably minimal risk of meaningful damage going overboard for a healthy person, but large doses can cause stomach issues for some people, and it seems unlikely to provide benefit beyond going beyond complete saturation. It looks like, of the studies you showed, the only one where they went for a large dosing for a long period of time was when experimenting with it on children with traumatic brain injuries. That's probably because the risk:reward skewed heavily towards reward there.

The 0 one is a meta study. It goes deeper into Huntington's 30g, Parkinson’s, elderly with cognitive decline, and supplementing for help with memory related tasks. I didn’t dive deep into all either because I saw what applied to me and decided to see the results.

I think dividing the dosages throughout the day would help offset the stomach issues some and there have been 5 year long studies showing creatine doesn’t have any major risks with 5-7% people experiencing GI issues during loading phases.

https://www.bodybuilding.com/content/6-side-effects-of-creat...