Actually you can do anything you want. You can not only invest on Btc :p but you can do things you want. Personally I use them for all my bills, and stuff I wanna buy. It's a good way to be anonymous and safe some real (paper) money. If you search it you will be surprised how many things you can do 
That's right there are many things that you can do with bitcoin and if you don't want to do anything then simply hold it for the future as that is the safest way of making profits by selling them when you see higher price in near future.
I completely agree. At the moment, just keep bitcoin in your wallet - the safest option. I am sure that in a few years it will make you a rich man
Yeah as investing them anywhere is a big risk as most of the investment places are scam and will eat away all your bitcoins so its better to play safe and keep them safe in you wallet as it is the safest way to make profits in long term.