1. Speculative/trading/buying coins hoping to get rich.
2. As a medium of exchange, currency to buy stuff just like you would for money.
3. As a means in itself to make money, i.e mining.
Also why did you get into bitcoin?
1. You were one of the first movers? You thought it was cool, interesting, you were here from the start?
2. Revolutionary ideas that it's going to change the world, banking system, etc.
3. You were just curious and then the more you looked into it, you saw how cool it was and promising(me).
4. Speculation, wanting to get rich.
I just use my bitcoin to buy some altcoin which will help me to make more profit and more bitcoin. There are time that I use my bitcoin to buy some stuff and you can really say that bitcoin is suits on become currency. Bitcoin will become more useful if you use it in buying some altcoin or doing trading.