They could not cause me any real grief. My profits from share dealing have always been considerably more than my losses - but I still take the view that one year the situation might change. It seldom pays to be over-confident in your own ability. I have never borrowed money to buy shares - I've always saved up until I can afford to buy them. Sometimes I've cancelled plans for an overseas holiday or to buy a new car simply so I can use that spare cash to buy more shares instead.
Some people do make a fortune buying shares with borrowed money.
I think it's too risky. Some people maintain that you should have a 'wide spread' of investments. I have experienced seeing a 500 investment increase to 4,500 in less than eighteen months. You might even do better than that or you might lose half your original investment. This may seem a rather silly question, but it is still worth asking.