Buying shares of stock is just another form of gambling disguised as investing.
If you are using a short term strategy like day trading then you are not investing anything . Some people buy stock for long term but sometimes people buy it for short term
Short term trading or day trading is equal to gambling so one have a more chances to lose their complete money in these things because most of the time need only luck to win. So if one want to make a money from share market then they must invest in some good companies and wait for few years to grow their business and your share prices.