But if you did your research well and leave the $10 in a stock with huge potential growth in the future, that could triple or even grow to one hundred percent in years if not decades. Of course, if you really need the money, simply don't invest.
Another person replied to me and mentioned about debt. I hadn't initially consider it because in my country, debt crisis is not really an issue unlike in the US or elsewhere so I didn't mean to be callous. If the person have debts and really need every penny and cents count, of course pay them off first before starting to invest; I'm not a financial advisor but that's the general advise that a qualified person will also make.
My very first comment is a counter to the idea that you have to be extremely rich or an institutional investor to start investing, which has never really been the case. You can start investing with any amount you can afford.