1) Your siblings won't want to hold it
2) They're easy maintinence
3) Interesting to study
4) Educational
5) Tarantula venom is not very potent
6) No matter where you are in the world, your are always within 3 feet of a spider, why not make it a gentle giant?
7) Tarantulas are beautiful
6) A great hobby
8) No brushing or vet bills
9) Breeding rare tarantulas is a great way to help an endangered species
And #10 the ultimate reason to have a tarantula is... I don't really know. There are so many... so what do you think email me and tell me what you think is the top reason, and i'll post it!