We’re talking about financials here so it’s referring to financial risk. A highly-qualified and skilled founder is forgoing the guaranteed opportunity to make $1m+ in the time they choose instead to work on their startup. They also risk harming their future earning potential and career prospects if they don’t already have a track record of success. A low-paid worker in this imaginary situation isn’t risking much of anything financially as they’ll (hopefully) get minimum wage either way.

(In practice a lot of small businesses owners use debt and that is where the financial risk lies for them).