30 years corresponds to the biggest boom in equities the world has ever seen. There is no guarantee it will continue, a 100% stock portfolio is very risky to live off of.

4% is the generally accepted safe withdrawal rate (inflation adjusted) from a portfolio for 30 years holding a mix of bond funds and equities. If you’re trying to live off of it for 50-60 years, 3-3.5% is the recommendation.