Often the same books get readapted over and over again as new TV shows -- think of how many TV series Sherlock Holmes alone spawned.
It's a good thing because far too often the TV adaptation can't measure up to the books, isn't given enough time to find an audience, or could benefit from an update.
Based on George R.R. Martin's A Song Of Ice And Fire series, Game of Thrones was a mega-hit but ended its run as one of TV's greatest disappointments.
Why did the series crash and burn like King's Landing on Game of Throne Season 8 Episode 5?
In general, the more faithful Game of Thrones was to the books, the better the TV series was. You can easily see this from the unevenness of Game of Thrones Season 2.
Tyrion's storyline as the acting Hand