Also known as "it's easy to become a rich man, if you start out as a rich man".
Realizing a positive real return is not very hard - just buy the index or some real estate. If you start with a large amount of capital, you can simply watch it multiply, and, for the adventurous, maybe risk some of it into more speculative deals.
If you start out with just the human capital of your hands and brain, any reasonable rate of return will be squashed by living expenses and basic quality of life, dependents etc. You will need many decades to build enough wealth using the same methods a rich man uses, and by that time your own human capital starts to depreciate and you are forced to move to a capital conservation strategy.
So, to make it big as a poor person, you always have to take on crazy risks that the rich never would and/or be exceptionally lucky, or be extraordinarily talented and hardworking - to an statistically implausible degree - so as to make your starting human capital much more valuable.
You will always find the rags to riches story presented as a tale of hard work and determination, but rarely will any "self made billionaire" acknowledge their immense luck. The entire VC space is basically an attempt from capital owners to cash in on this statistically rare phenomenon, by hedging their bets on the destinies of many many people attempting to make it big.