Who are the other members in his organization? Is he the only founder? (Does he own the other 95%?) How much funding does it already have/does it need in the fu

Who are the other members in his organization? Is he the only founder? (Does he own the other 95%?) How much funding does it already have/does it need in the future? (Dilutive potential) What are your alternatives? If you have a 250k salary job elsewhere and you have a family, the safety might be worth it. What are your circumstances? The value of a stake in a startup is highly context-sensitive. jaltucher brought up some great questions you should answer first, so you should take a look at his questions first. Good luck.