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.
Yes in short term people are just guessing the price can move either up or down so winning will be based on just by luck so for short term share market investment is not good.