Bitcoin is a safe investment. But buying some Altcoins too is a good idea. I suggest buying a bit of both coins. Both Altcoins go up and down, so if you have both you have a win win situation if you invest carefully.
I don't have enough money to invest in bitcoin just in altcoins since I can have capital from the campaign I joined to make an investment in it. It should be better to have both investment at a time because both are having pumps and dumps to take risk. To have a secure investment, taking the two will give opportunity to not lose any amount when investing.
Why you dont have enough money to buy bitcoin? you can buy with any amount, no minimum required to buy bitcoin. Bitcoin still grow up and you still can get profit from it.