Is this genuinely the advice you'd give to someone who's less experienced in life? No wonder society is the way it is, most people have extremely low ambitions and then don't even bother working on those.
Maybe an intermediate position is to say, "Before you attempt to beat the odds, make sure you can survive the odds beating you." Because the odds are, they will.
People deterred by someone else's words usually internally hesitated anyway.
Plenty of extremely successful people, including plenty of billionaires, started out with a paycheck with an employer, often for many many years. Plenty more live very comfortable lives. Your framing as the former is somehow "lacking ambition" is just wrong.