damn good idea, i'm gonna join the airforce in the summer, but the rangers ain't no walk in the park, it's something to seriously think about
Only about 25% of candidates make it through I believe is the figure.
Still a high number when compared to the French Foreign Legion where only 8-10% of people make it in.
I would say that it is your own life, man. Finding something that you love doing and makes you happy is a good thing. I would make sure, as with any big life step, that you properly educate yourself on the subject. Talk to people that have already done Airborne and Ranger. Get their perspective. It isn't selfish to do something that you like doing.
As for it being "normal", it is something that you are interested it. Of course you are going to be enthusiastic and pursue knowledge in the area. It's only natural. It would happen with a lot of things!
Feel free to keep in contact, and instant message me whenever.
~Shaun