If bitcoin exchanges can be "scammed" why is bitcoin better? Reading a post about someone getting scammed in an exchange and thinking about becoming a bitcoin user, now I am wary about this form of currency exchange.

If the exchanges can scam you, see How to denounce a scam exchange, such as this exchange called BitNake, then why would I use this form of currency? At least with US Dollars we are insured up to $250,000 per bank account by the FDIC.
Because you and I are not exchanges and Bitcoin is Peer to Peer. Exchanges are irrelevant to the question whether Bitcoin is "better".

Before you start, make sure to read all the introductory material on www.bitcoin.org so you know what you're doing and are choosing the right wallet and exchange.

Some exchanges are scams. Some are not, but may go out of business at any time, just like any company. Hopefully the ones linked above are at least not scams.

Use a reputable exchange (or another method, like localbitcoins) to buy Bitcoins and immediately withdraw them to your own local wallet. Don't leave Bitcoins on an exchange or web wallet any longer than required.

I've never heard of BitNake, but just the name screams scam. Stay away.