See there as such is no risk in buying 3-4 bitcoins.
This is because the value of bitcoins fluctuates around a stable value.
That is consider today's scenario the value of bitcoins is stable around 1100$ but fluctuates a bit.
So if you purchase 3-4 bitcoins and if the price rise or growth rate of BTC is slow you won't loose much.
3-4 bitcoins today is quite a lot of money for beginners, especially for people who live in third world countries. You will probably say that past years show us that Bitcoin is stable and futureproof investment. A lot of things happen right now according to cryptocurrencies. Many goverments around the world started regulating them! Just look what happened to the Bitcoin price when China announced the ban of exchanges.