Adjusting one's lifestyle to decrease expenses is a much better way to "create" wealth.
In the investing world, index funds are very useful, and they often beat inflation by a few percentage points. But that return is only significant when you have tons of money.
As I pointed out in another comment, turning $100k into $200k (adjusted for inflation) would take 20 years, assuming index funds grow 7% every year and inflation is a constant 3%.
But if you have, say, $100k in income and $100k in the bank, you're going to "make" far more money by decreasing your costs by $20k than you could by investing that $100k (on average).
Obviously there are people who get lucky buying houses and whatnot, but no one can reliably double $100k in 5 years.
I thought the average return just from the stock market was 7%.
I am a total novice, and have fairly little invested, but those are the sort of numbers that pension projects are based on.
If you can keep you personal burn rate low, and over time invest a significant amount of money at 5% return for 10 years, the interest really starts to snowball.
If the average return from an index fund is 7% and inflation is, say, 3%, then you're making an extra 4%.
If you're investing $100k, you'll double the value of your money in 20 years. That's not great for someone who doesn't have much other cash and could use that $100k over those 20 years for significant lifestyle improvements.