Hey... its good to see a post from you again! I agree 100% with you about discouraging someone from leaving their job. I am still trying to figure out long term plan to make money online. It make take 6 months, 1 yr or mabye even 5yrs! But to me, that is much better than working for a regular day job for the next 30 yrs (even if you enjoy what you are doing). To be able to make residual income online from starting from zero is quite an accomplishment and as long as one continues to keep up to date with how internet marketing changes and incorporate these changes into their online ventures, he/she should be able to stay on top of the money making ideas that they started. Anyway.....I am beginning to ramble......thank you Night Owl for all of your suggestions.
Quitting yoru job for adsense as sole income stream is not a great idea. The fluctuation of earnings, of your traffic, and the possibility that they could disable your acct should detour you from this. Try to diversify your revenue stream. Maybe membership sites.
Adsense is a great place to make money, or may be as your side income. However, you can't depend 100% to it, as sometimes our site could perform below expectation. Don't retreat easily. There's still a lot of opportunities waiting for you.
The thing about adsense is that if you have a steady traffic, you will definitely make money, provided that the ads are relevant and inline with the interests of the visitors. If you can be sure of that, provide quality content to visitors and keep the traffic steady, he can definitely leave his job, and also spending time fully on adsense sites if you know what you are doing is a very good thing to do. I repeat, If You Know What You Are Doing.
He should NOT leave his job! If he really wants to, then he should make his current job part time, but Ive never heard of someone making Adsense their prime source of income. Maybe theres a reason for that.