In my view, they all exist on the same continuum, and there's often no good reason to use these terms individually: every decision about where to place your money is a "gamble", is "speculation", is an "investment", and is "saving" all at the same time.
The only common attribute from the above terms that you stand to gain or lose value in the process of these activities. The differences are extremely important because
gambling is the opposite of investing. A
gamble involves an independent event of pure chance where the person placing the bet has no influence on the outcome, such as a dice wager. An
investment involves a meaningful choice made by the person funding it (with their time or money), such as buying a used car.
Speculation refers to an investment made with the intent of reselling in the short term for a profit.
Saving refers to an investment made with no intent in reselling in the short term for a profit. Presumably, both speculators and savers assume the thing they are investing in will generate a profit on some future timeframe.
They all exist on the same continuum, is all I am saying. Some forms of what most would call "gambling", e.g. Texas Holdem Poker, are "investing" to the point where many people earn a living doing do it. And lots of things people call "investing" actually perfectly fits your definition of gambling. (Nobody who invests in Bitcoin has any influence on the outcome, for instance).
The difference in all of them is simply the amount of information one possesses.
I get that we have these terms for a reason, and I'm not against using them individually, but I think it's worth understanding the exact distinction because... I think a lot of people get it wrong, especially in the crypto universe: when somebody says, "my life savings is in Bitcoin" I cringe: that's an wager they basically know nothing about, and could drop drastically. On the other hand, calling a speculation on a memecoin "gambling" can be a bit harsh when somebody has at least some idea of how "hot" the new meme is becoming based on its market momentum and the promoters behind it.