For a completely different perspective on this advice (the advice given here is the consensus view on how to build wealth) read "Unscripted" or "The Millionaire Fastlane" by MJ Demarco.
Your advice is to use your savings to generate capital growth via the stock market via index funds. This isn't necessarily good advice. It may be, and it's common advice, but the books I mentioned explicitly advise against doing that.
My advice is living on 50% of income, and saving. It doesn’t matter if income comes from business or a job. Even if you don’t think index funds will grow, which is going against 100+ years of historical returns, you have to park money somewhere for capital preservation.
After saving one year’s expenses as cash in the bank, where would you park savings for low-risk passive capital preservation? Cash gets destroyed by inflation. Bond yields are too low. The historical track record of 20 years in a good stock index is unbeatable, no matter what year you started.
Where do you keep your savings, right now?
Even if you focus on growing capital by starting a business (what The Millionaire Fastlane recommends), you still have to park the profit somewhere.
My advice applies to whether one chooses to start a business or not.