Compound interest? Where? The interest rates are such that inflation would destroy whatever gain you have. Nearly all savings accounts are paying an annual yield of less than 1%! That means WITH compounding, you're looking at a 1% or lower gain. Inflation is typically between 1-4%, with 2% being the benchmark in terms of financial planning, though admittedly in April, we had slightly negative inflation, but that trend won't continue.
Investing is the only way to build wealth. It's impossible to save your way to financial freedom. If you make an average of $100K per year from age 30-60, that's $3 million in income. Assuming about 35% in state, local and federal taxes, that leaves you with $65K per year. Now, you're saving 10% of that per year, that's $6,500 saved per year. With a 1% rate, at the end of 30 years, you have about $229K. Assuming you live to be 80, that's $229K that needs to earn enough to pay your bills. Even if you saved 20%, you'd still not even have $500K at the end of 30 years.
With the same 20% savings rate and some reasonably smart investing (12% returns,) then you'd end up with over $3.5 million over the same period. If that investing is in real estate, you could potentially earn that gain tax free (or tax reduced) because building depreciation percentages can generally exceed the "profit" from real estate cashflow. On top of that, a 1031 exchange means you can keep selling and trading up to larger and larger real estate without paying a capital gains tax, which means you build even more net worth that can then be leveraged to buy more properties. Most millionaires get there because of property, very, very rarely because they save their way to it. A typical middle-class wage doesn't lend itself well to saving your way to millions. The math just doesn't work, the tax code also doesn't support it.
Frugality isn't the key to success. The $30 you save by washing your own car is peanuts compared to the value of that time doing something more productive (like sourcing real estate or researching investments.) Frugality can actually cost you more money because of the time-value of money. But admittedly many of us have inherited our parents/grandparents' Depression Era, middle-class ethos. It's a classic example of Rich Dad Poor Dad.