A) I can't answer that question, but just so everyone's clear: the money you invest in megacorps doesn't go to megacorps. It goes to other shareholders that owned shares of the megacorps and a small percentage would go to the trading platform and the capital market itself. If you're investing in ETFs, the company that manages the fund will likely get a small management cut too. Either way, it mostly goes to people seeking to lower or eliminate their stake on the companies you invest in. It's more like a horse racing thing: You bet on a horse, but the horse doesn't get your money.
B) Yes, all investments are gambles, to an extent. The only difference is the different levels of risk and reward. And in finances, betting a certain amount against what you hope for if called "hedging". It basically means "I want X to happen, but if Y happens, I want my ass covered too." This concept may be useful to you.
Personally, many consider me an anarchist because I don't believe in the legitimacy of any power that anyone holds against anyone else whatsoever (except my mom's), but I'm also a pragmatist. The world will follow its course and we can only do so much. We can hold our beliefs and make the marginally small pushes we can afford to make towards a world we believe is better, but we also must survive and ensure our own stability given the current state of the world as is. That means adapting to current reality.
Now, be warned. If your investments do really well and you find yourself swimming with money in the future, there comes a point where money becomes poison. The way I see it there are only 3 amounts of money: Not enough, comfortable enough and too much.
Good for you for making ends meet. Allow yourself to feel proud of your accomplishment. Surviving in this economy is no easy thing.
Source: I'm a financial consultant that holds virtually no assets.
Edit: Horse racing for clarity and typo.