There are several reasons why people gravitate towards the Calvinistic theological system.
Calvinism has a reputation for being a standard of historic Christianity, even though some of its core doctrines were not known in the early church and were not invented until the 5th century, and some not until the 16th century. So many are open to Calvinism because of this reputation, but most do not commit to it for that reason.
Others are drawn to Calvinism because it is an airtight theological system. People with a philosophical bent gravitate towards this aspect of Calvinism. But again, this is not usually what causes people to fully embrace Reformed Theology.
The #1 reason people commit to Calvinism is a misunderstanding of a few passages of Scripture. Once a false interpretation of some passages like Romans 9, Ephesians 1, and others are embraced, the rest is history. The false interpretation of these passages then becomes the lens through which all other passages in the Bible are interpreted. For this reason, it is imperative that biblical interpretations are made available to those on the fence.
So, what is the big deal? Well, the most dangerous aspect of Calvinism is that it replaces the correct interpretation of Scripture with a false interpretation. This causes many important passages of God’s word to be made null and void. There are other dangers as well, but this is the key problem.
This is discussed in the video below: