A number of reasons. Firstly, their care is more advanced than slot of other species and husbandry needs to be dialed in 100% before arrival. Getting husbandry perfect is always tough as a beginner and chondros do not easily bounce back from those kinds of errors. Also, as your first snake, you’re going to want to hold it. Probably a lot. Not only do babies have very delicate spines, but their teeth are very formidable. It’s not going to be the kind of snake you can man-handle without hurting it or yourself
Not to generalize, as I have heard of very tame GTPs, but I guarantee you the keepers on this forum who own chondros rarely ever handle them. And they are all VERY experienced.
If you want something feisty, arboreal, and highly colored, an ATB is a much better option and would give you practice so you can perfect thehusbandry a chondro requires.