1. It's Illegal without a licence.
2. You need a licence because it is extremely dangerous.
3. You could blow yourself up (Vapourised alcohol is extremely inflammable).
4. You haven't thought this through, so you probably don't know what you're doing. Distilling is also dangerous because if you get it wrong you will almost certainly kill yourself if you don't take off the heads and tails properly. If you don't know what the heads and tails are then perhaps you should go and buy a bottle instead. Besides, it is a long, complicated and time consuming thing to do and quite frankly very very very boring.