Sure, not always. To clarify: I mean stocks are shares in companies, which generally generate profits. Yes, some companies may not, or may even go under, but none of this is an issue if you hold a diversified set of stock and bond indexes for the long haul (I'm talking about equities as an asset class, not any one stock). Stocks are stakes in companies - bonds pay a risk premium - crypto, gold, etc... don't generate income, which by definition makes them speculative.
I know what it means but have no idea how profitable it is or whether those profits are guaranteed or fleeting. Best I can tell it's like any service (business, not investment): depending on demand and competition, you can make money for a time, then stop at some point. So far that has never been an issue for people investing in the global stock market (i.e. the global stock market persists even as individual stocks, sectors, industries, even whole countries have crashed in the past).
Not always, tons of companies are losing money but the share price goes up.