I think you don't the meaning of share market investment that's why you telling that investing in share market is guessing game. But real scenario is your buying a business if you don't understand the company business then don't invest in that company. So as per me share market investment for long term is totally different from gambling.
Not everyone buying shares for long term some people just treat it like day trading and nothing special about that. The fast market and high volume is the reason people use it for day trading
What you said is correct, every one want's fast money and at the end who ever goes for these kind of fast money they will end up losing all their money in super fast way. If you check the share market history most of the day traders has lost money but who ever used share market for long term investment tool only made very good profits. So share market is for making profits in long term but not for short term.
Yes even share market and gambling are compared for many reasons, in my perspective share market is good if you go for long term.
In my friends, many people have achieved big amounts of money from share market for keeping their stocks for around 10 years. But there is no history similar to this from gambling.