There are people that find investing in alt very attractive from profit point of view, believing that the value of particular coin will increase so so much. It's easier to imagine that something with the price of 0.3 dollars goes on, I don't know, 500 dollars for example, than to see how bitcoin climb on fifty thousand dollars. Maybe it is the best decision to invest in bitcoin but there will always be people with different vision, especially if there is wide offer to choose.
Although it is always good to buy bitcoin and specially in such a low price but I think that there are so many other altcoin which are trading in low price but still they have good potential so low investors can also keep and hold such coins which have good potential. I think that Etherium price is also trading low and even if a person will hold Etherium they can also get good profit from there.