I don't classify gambling as any means of investment. Just as you say gambling is like a means of one doubling his money which comes with risk of one winning or losing. But gambling doesn't actually means that one will always lose all his money , the money that's always at risk in gambling is the money that's being staked. So is only a irresponsible gambling that will always go all in. With his hard earn funds. Due to greed of wanting to hit a huge jackpot, but still gambling is not an investment so whenever stake your money be ready for anything, either you win or you lose.
I don't know if some people don't understand and think that gambling can be called or considered a sort of investment but it's not, however, some casinos do allow us to make investments with them in their bankrolls, probably, and they give us a small percentage of the profits to us. This is how it used to work in the past, nowadays, some casinos offer investments as well and you get a specific APY for your investment, Blackjack.fun is one of such casinos available right now in the market.
However, the APY might not be very high, and most people these days want to earn a lot of money with what they have which is the reason why most people are getting into cryptocurrencies these days because they believe they can earn a lot of money from cryptocurrency investments.
