Robert Kiyosaki made his fortune from selling "Rich Dad, Poor Dad" book, not by using the methods that are actually in the book. the Rich Dad doesn't exist, unless there is something he is hiding from everyone.
However, he is correct in that the bitcoin price will reach $120,000 very soon. It probably won't happen next year though, but maybe in two years.
There's a lot of learnings we can read from his book but I also believe that he apply all of it in his life. He made his fortune due to his books since this is so hype and many people want to acquire since they thought that they can learn something and apply it for theirselves. But at the end of the day its always up to our effort made before we can see a result and there's no book can help us regarding on this situation.
For bitcoin maybe he base it all on its past all time high result and there's a high chance that this one could possibly happen but I also believe that we are far to reach that price considering some negative happenings that can affect the price of bitcoin.