It is supported to buy the Bitcoin with the FIAT but the problem is that with the current value of the Bitcoin best thing that can give you long-term profit is trading with this coin and again buying it when it enters the big fluctuation state. The people profited the most when the Bitcoin was just released and when they recognized the opportunity they grabbed it. I regretted a little bit because I didn't recognize the true power of decentralized currency and I didn't saw the possible progress of the Bitcoin that came to be true.
It is never too late to buy Bitcoin as it will for sure rise in a value within 5 years but don't expect the big profit only from this one coin if you have invested poorly.