Usually they recommend you to diversify your investment, so you avoid losses.
But as a real approach, having $1.5k, would you invest in how many cryptocurrencies ?
What if I invest little by little, only in Bitcoin, would that work as well ?
Work or not an investment depends on your analysis and strategy, you want to invest a lot at the same time or investment from little by little if you do not have knowledge on the investment then it is not work. $1.5k I think it's not enough if you invest only in bitcoin, in my opinion it actually makes your profits smaller because the value of bitcoin and bitcoin fluctuations is relatively slow from altcoin, but if you choose a small risk then bitcoin is the best thing.
Its not good to put all your money in one investment its better if you divided by two or three. But make sure you put it to those crypto that have potential or find coin to invest that can give tou good profit. So diversify investment is really good to do especially if you have choosen asset to invest. But if you have only one invest coin then its better to not put all your money to it, just enough amount only, so the risk is also lower.