Speculating is not about what you think will happen. It's about what you think other people think will happen. It's about the market, not the inherent value of the stock.

Good investing is about buying into something you think is undervalued.

If a business has been "shown" to be profitable and stable, as you say, then its stock price will be high enough to reflect that, and it's probably not undervalued, unless you know something special about it. All you can expect it to receive a steady small stream of dividends, or sell the stock sometime in the future for roughly the same amount you paid for it originally. That's not really "investing", that's just swapping cash for stocks. Save yourself some risk and just put your money in an index fund instead.

This is basically the age-old debate between "growth" vs. "value" investing. Either side has some arguments; personally I prefer to stay out of it.

One of the most common and simplistic valuation methods is using the Expected Value of the Net Present Value of Future Earnings. Past information can be an indicator, but is in a sense "Sunk."

I agree about the value of Ben Graham, however, there's no set definition for what investing is really all about.

If you want to argue what the most rational approach to investing is, sure, that's fine.

However, there are a lot of ways to skin the cat these days. You can high frequency trade; you can slap puts on stocks if you have a skill as a short; you can use calculated hedges and skim points; you can carry trades through currency variations; you can buy and flip based on market panic (or short temporarily based on irrational euphoria), with no intention for long term holdings or long term profit concerns.

I think more people (less skilled professionals) can invest in the Ben Graham model, over a long period of time, than any of the other approaches. But, a select few have turned out to be extraordinary at the other approaches, and have made great fortunes that way as well.