Is Bitcoin like other commodities that are prone to ups and downs in value?
Yes.
Is there a risk of a crash like in the stock market of a country?
Yes.
Will the value of bitcoin just keep on increasing forever?
Probably not. It will be volatile for quite a while, then eventually probably steady off, but it will always fluctuate just like any other currency. Nobody can predict what is going to happen to cryptos in the long run. Weigh up the risks and choose the gamble or not, that's the fun of it.